diff --git a/.php_cs b/.php_cs
deleted file mode 100644
index 9fb8baa..0000000
--- a/.php_cs
+++ /dev/null
@@ -1,32 +0,0 @@
-<?php
-
-return PhpCsFixer\Config::create()
-    ->setRules([
-        '@PSR2' => true,
-        'array_syntax' => ['syntax' => 'short'],
-        'binary_operator_spaces' => ['align_double_arrow' => false, 'align_equals' => false],
-        'blank_line_after_opening_tag' => true,
-        'blank_line_before_return' => true,
-        'cast_spaces' => true,
-        'concat_space' => ['spacing' => 'none'],
-        'declare_strict_types' => true,
-        'method_separation' => true,
-        'no_blank_lines_after_class_opening' => true,
-        'no_spaces_around_offset' => ['positions' => ['inside', 'outside']],
-        'no_unneeded_control_parentheses' => true,
-        'no_unused_imports' => true,
-        'phpdoc_align' => true,
-        'phpdoc_no_access' => true,
-        'phpdoc_separation' => true,
-        'pre_increment' => true,
-        'single_quote' => true,
-        'trim_array_spaces' => true,
-        'single_blank_line_before_namespace' => true,
-    ])
-    ->setFinder(
-        PhpCsFixer\Finder::create()
-            ->in(__DIR__ . '/src')
-            ->in(__DIR__ . '/tests')
-    )
-    ->setRiskyAllowed(true)
-    ->setUsingCache(false);
diff --git a/.travis.yml b/.travis.yml
index 8f8a68b..bf26816 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,6 +31,7 @@ install:
 script:
   - vendor/bin/phpunit $PHPUNIT_FLAGS
   - if [[ $STATIC_ANALYSIS != "" ]]; then vendor/bin/ecs check src tests; fi
+  - if [[ $STATIC_ANALYSIS != "" ]]; then vendor/bin/phpstan.phar analyse src tests --level max --configuration phpstan.neon; fi
 
 after_success:
   - |
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 7d2f451..b2d5f9e 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -6,31 +6,40 @@ code base clean, unified and future proof.
 
 ## Branch
 
-You should only open pull requests against the master branch.
+You should only open pull requests against the `master` branch.
 
 ## Unit-Tests
 
 Please try to add a test for your pull-request. You can run the unit-tests by calling:
 
-```
-bin/phpunit
+```bash
+vendor/bin/phpunit
 ```
 
 ## Travis
 
-GitHub automatically run your pull request through Travis CI against PHP 7. 
-If you break the tests, I cannot merge your code, so please make sure that your code is working 
-before opening up a Pull-Request.
+GitHub automatically run your pull request through Travis CI.
+If you break the tests, I cannot merge your code, so please make sure that your code is working before opening up a Pull-Request.
 
 ## Merge
 
 Please allow me time to review your pull requests. I will give my best to review everything as fast as possible, but cannot always live up to my own expectations.
 
-## Coding Standards
+## Coding Standards & Static Analysis
 
-When contributing code to PHP-ML, you must follow its coding standards. It's as easy as executing `./bin/php-cs-fixer fix` in root directory.
+When contributing code to PHP-ML, you must follow its coding standards. To do that, just run:
+
+```bash
+vendor/bin/ecs check src tests --fix
+```
+[More about EasyCodingStandard](https://github.com/Symplify/EasyCodingStandard)
+
+Code has to also pass static analysis by [PHPStan](https://github.com/phpstan/phpstan):
+
+```bash
+vendor/bin/phpstan.phar analyse src tests --level max --configuration phpstan.neon
+```
 
-More about PHP-CS-Fixer: [http://cs.sensiolabs.org/](http://cs.sensiolabs.org/)
 
 ## Documentation
 
diff --git a/composer.json b/composer.json
index 7b774f2..b08d6f8 100644
--- a/composer.json
+++ b/composer.json
@@ -11,19 +11,24 @@
             "email": "arkadiusz.kondas@gmail.com"
         }
     ],
-    "autoload": {
-        "psr-4": {
-            "Phpml\\": "src/Phpml"
-        }
-    },
     "require": {
         "php": "^7.1"
     },
     "require-dev": {
         "phpunit/phpunit": "^6.4",
-        "friendsofphp/php-cs-fixer": "^2.4",
-        "symplify/easy-coding-standard": "dev-master as 2.5",
-        "symplify/coding-standard": "dev-master as 2.5",
-        "symplify/package-builder": "dev-master#3604bea as 2.5"
+        "symplify/easy-coding-standard": "v3.0.0-RC3",
+        "symplify/coding-standard": "v3.0.0-RC3",
+        "symplify/package-builder": "v3.0.0-RC3",
+        "phpstan/phpstan-shim": "^0.8"
+    },
+    "autoload": {
+        "psr-4": {
+            "Phpml\\": "src/Phpml"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Phpml\\Tests\\": "tests/Phpml"
+        }
     }
 }
diff --git a/composer.lock b/composer.lock
index e10b2d8..4236a2d 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "0b709f785c1e62498755f557e49e1ba4",
+    "content-hash": "032ab1160f58aff496453a86648f7012",
     "packages": [],
     "packages-dev": [
         {
@@ -247,16 +247,16 @@
         },
         {
             "name": "friendsofphp/php-cs-fixer",
-            "version": "v2.8.1",
+            "version": "v2.8.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/FriendsOfPHP/PHP-CS-Fixer.git",
-                "reference": "04f71e56e03ba2627e345e8c949c80dcef0e683e"
+                "reference": "b331701944cbe492e466d2b46b2880068803eb08"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/FriendsOfPHP/PHP-CS-Fixer/zipball/04f71e56e03ba2627e345e8c949c80dcef0e683e",
-                "reference": "04f71e56e03ba2627e345e8c949c80dcef0e683e",
+                "url": "https://api.github.com/repos/FriendsOfPHP/PHP-CS-Fixer/zipball/b331701944cbe492e466d2b46b2880068803eb08",
+                "reference": "b331701944cbe492e466d2b46b2880068803eb08",
                 "shasum": ""
             },
             "require": {
@@ -323,7 +323,7 @@
                 }
             ],
             "description": "A tool to automatically fix PHP code style",
-            "time": "2017-11-09T13:31:39+00:00"
+            "time": "2017-11-19T22:51:25+00:00"
         },
         {
             "name": "gecko-packages/gecko-php-unit",
@@ -1219,16 +1219,16 @@
         },
         {
             "name": "phpspec/prophecy",
-            "version": "v1.7.2",
+            "version": "1.7.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpspec/prophecy.git",
-                "reference": "c9b8c6088acd19d769d4cc0ffa60a9fe34344bd6"
+                "reference": "e4ed002c67da8eceb0eb8ddb8b3847bb53c5c2bf"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/c9b8c6088acd19d769d4cc0ffa60a9fe34344bd6",
-                "reference": "c9b8c6088acd19d769d4cc0ffa60a9fe34344bd6",
+                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/e4ed002c67da8eceb0eb8ddb8b3847bb53c5c2bf",
+                "reference": "e4ed002c67da8eceb0eb8ddb8b3847bb53c5c2bf",
                 "shasum": ""
             },
             "require": {
@@ -1240,7 +1240,7 @@
             },
             "require-dev": {
                 "phpspec/phpspec": "^2.5|^3.2",
-                "phpunit/phpunit": "^4.8 || ^5.6.5"
+                "phpunit/phpunit": "^4.8.35 || ^5.7"
             },
             "type": "library",
             "extra": {
@@ -1278,7 +1278,43 @@
                 "spy",
                 "stub"
             ],
-            "time": "2017-09-04T11:05:03+00:00"
+            "time": "2017-11-24T13:59:53+00:00"
+        },
+        {
+            "name": "phpstan/phpstan-shim",
+            "version": "0.8.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/phpstan/phpstan-shim.git",
+                "reference": "0b174a61fd99dea61f15ea6bd3bc424389f273d4"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/phpstan/phpstan-shim/zipball/0b174a61fd99dea61f15ea6bd3bc424389f273d4",
+                "reference": "0b174a61fd99dea61f15ea6bd3bc424389f273d4",
+                "shasum": ""
+            },
+            "require": {
+                "php": "~7.0"
+            },
+            "provide": {
+                "phpstan/phpstan": "0.8"
+            },
+            "bin": [
+                "phpstan.phar"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "0.8-dev"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "PHPStan Phar distribution",
+            "time": "2017-10-24T04:16:00+00:00"
         },
         {
             "name": "phpunit/php-code-coverage",
@@ -1346,16 +1382,16 @@
         },
         {
             "name": "phpunit/php-file-iterator",
-            "version": "1.4.2",
+            "version": "1.4.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-file-iterator.git",
-                "reference": "3cc8f69b3028d0f96a9078e6295d86e9bf019be5"
+                "reference": "8ebba84e5bd74fc5fdeb916b38749016c7232f93"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-file-iterator/zipball/3cc8f69b3028d0f96a9078e6295d86e9bf019be5",
-                "reference": "3cc8f69b3028d0f96a9078e6295d86e9bf019be5",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-file-iterator/zipball/8ebba84e5bd74fc5fdeb916b38749016c7232f93",
+                "reference": "8ebba84e5bd74fc5fdeb916b38749016c7232f93",
                 "shasum": ""
             },
             "require": {
@@ -1389,7 +1425,7 @@
                 "filesystem",
                 "iterator"
             ],
-            "time": "2016-10-03T07:40:28+00:00"
+            "time": "2017-11-24T15:00:59+00:00"
         },
         {
             "name": "phpunit/php-text-template",
@@ -2418,7 +2454,7 @@
         },
         {
             "name": "symfony/config",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/config.git",
@@ -2480,16 +2516,16 @@
         },
         {
             "name": "symfony/console",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "099302cc53e57cbb7414fd9f3ace40e5e2767c0b"
+                "reference": "63cd7960a0a522c3537f6326706d7f3b8de65805"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/099302cc53e57cbb7414fd9f3ace40e5e2767c0b",
-                "reference": "099302cc53e57cbb7414fd9f3ace40e5e2767c0b",
+                "url": "https://api.github.com/repos/symfony/console/zipball/63cd7960a0a522c3537f6326706d7f3b8de65805",
+                "reference": "63cd7960a0a522c3537f6326706d7f3b8de65805",
                 "shasum": ""
             },
             "require": {
@@ -2544,11 +2580,11 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-12T16:53:41+00:00"
+            "time": "2017-11-16T15:24:32+00:00"
         },
         {
             "name": "symfony/debug",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/debug.git",
@@ -2604,7 +2640,7 @@
         },
         {
             "name": "symfony/dependency-injection",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/dependency-injection.git",
@@ -2674,7 +2710,7 @@
         },
         {
             "name": "symfony/event-dispatcher",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/event-dispatcher.git",
@@ -2737,7 +2773,7 @@
         },
         {
             "name": "symfony/filesystem",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
@@ -2786,7 +2822,7 @@
         },
         {
             "name": "symfony/finder",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/finder.git",
@@ -2835,7 +2871,7 @@
         },
         {
             "name": "symfony/http-foundation",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/http-foundation.git",
@@ -2888,16 +2924,16 @@
         },
         {
             "name": "symfony/http-kernel",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/http-kernel.git",
-                "reference": "371ed63691c1ee8749613a6b48cf0e0cfa2b01e7"
+                "reference": "a2a942172b742217ab2ccd9399494af2aa17c766"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/http-kernel/zipball/371ed63691c1ee8749613a6b48cf0e0cfa2b01e7",
-                "reference": "371ed63691c1ee8749613a6b48cf0e0cfa2b01e7",
+                "url": "https://api.github.com/repos/symfony/http-kernel/zipball/a2a942172b742217ab2ccd9399494af2aa17c766",
+                "reference": "a2a942172b742217ab2ccd9399494af2aa17c766",
                 "shasum": ""
             },
             "require": {
@@ -2970,11 +3006,11 @@
             ],
             "description": "Symfony HttpKernel Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-13T19:37:21+00:00"
+            "time": "2017-11-16T18:14:43+00:00"
         },
         {
             "name": "symfony/options-resolver",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/options-resolver.git",
@@ -3201,7 +3237,7 @@
         },
         {
             "name": "symfony/process",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/process.git",
@@ -3250,7 +3286,7 @@
         },
         {
             "name": "symfony/stopwatch",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/stopwatch.git",
@@ -3299,7 +3335,7 @@
         },
         {
             "name": "symfony/yaml",
-            "version": "v3.3.12",
+            "version": "v3.3.13",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/yaml.git",
@@ -3354,16 +3390,16 @@
         },
         {
             "name": "symplify/coding-standard",
-            "version": "dev-master",
+            "version": "v3.0.0-RC3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/Symplify/CodingStandard.git",
-                "reference": "309fd562066cdc86b81375ff080b1ee2f900778e"
+                "reference": "0a3958f1cb6ce733def98f3abdf52a4e6c723879"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/Symplify/CodingStandard/zipball/309fd562066cdc86b81375ff080b1ee2f900778e",
-                "reference": "309fd562066cdc86b81375ff080b1ee2f900778e",
+                "url": "https://api.github.com/repos/Symplify/CodingStandard/zipball/0a3958f1cb6ce733def98f3abdf52a4e6c723879",
+                "reference": "0a3958f1cb6ce733def98f3abdf52a4e6c723879",
                 "shasum": ""
             },
             "require": {
@@ -3382,6 +3418,11 @@
                 "symplify/package-builder": "^2.5|^3.0"
             },
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.0-dev"
+                }
+            },
             "autoload": {
                 "psr-4": {
                     "Symplify\\CodingStandard\\": "src",
@@ -3394,20 +3435,20 @@
                 "MIT"
             ],
             "description": "Set of Symplify rules for PHP_CodeSniffer.",
-            "time": "2017-11-16 00:38:24"
+            "time": "2017-11-18T01:05:00+00:00"
         },
         {
             "name": "symplify/easy-coding-standard",
-            "version": "dev-master",
+            "version": "v3.0.0-RC3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/Symplify/EasyCodingStandard.git",
-                "reference": "4bac5271050f063b4455bd870cc215e0db57ddf8"
+                "reference": "7f2e7728a184c72945da482b23eb05b796f6502c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/Symplify/EasyCodingStandard/zipball/4bac5271050f063b4455bd870cc215e0db57ddf8",
-                "reference": "4bac5271050f063b4455bd870cc215e0db57ddf8",
+                "url": "https://api.github.com/repos/Symplify/EasyCodingStandard/zipball/7f2e7728a184c72945da482b23eb05b796f6502c",
+                "reference": "7f2e7728a184c72945da482b23eb05b796f6502c",
                 "shasum": ""
             },
             "require": {
@@ -3440,6 +3481,11 @@
                 "bin/easy-coding-standard.php"
             ],
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.0-dev"
+                }
+            },
             "autoload": {
                 "psr-4": {
                     "Symplify\\EasyCodingStandard\\": "src",
@@ -3455,20 +3501,20 @@
                 "MIT"
             ],
             "description": "Use Coding Standard with 0-knowledge of PHP-CS-Fixer and PHP_CodeSniffer.",
-            "time": "2017-11-16 15:36:21"
+            "time": "2017-11-18T14:13:17+00:00"
         },
         {
             "name": "symplify/package-builder",
-            "version": "dev-master",
+            "version": "v3.0.0-RC3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/Symplify/PackageBuilder.git",
-                "reference": "3604beadddfdee295b978d87475a834810a0ffd4"
+                "reference": "c86f75165ed2370563a9d4ff6604bbb24cffd5e5"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/Symplify/PackageBuilder/zipball/3604beadddfdee295b978d87475a834810a0ffd4",
-                "reference": "3604beadddfdee295b978d87475a834810a0ffd4",
+                "url": "https://api.github.com/repos/Symplify/PackageBuilder/zipball/c86f75165ed2370563a9d4ff6604bbb24cffd5e5",
+                "reference": "c86f75165ed2370563a9d4ff6604bbb24cffd5e5",
                 "shasum": ""
             },
             "require": {
@@ -3486,6 +3532,11 @@
                 "tracy/tracy": "^2.4"
             },
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.0-dev"
+                }
+            },
             "autoload": {
                 "psr-4": {
                     "Symplify\\PackageBuilder\\": "src"
@@ -3496,7 +3547,7 @@
                 "MIT"
             ],
             "description": "Dependency Injection, Console and Kernel toolkit for Symplify packages.",
-            "time": "2017-11-16T01:05:48+00:00"
+            "time": "2017-11-17T13:58:38+00:00"
         },
         {
             "name": "theseer/tokenizer",
@@ -3656,31 +3707,12 @@
             "time": "2016-11-23T20:04:58+00:00"
         }
     ],
-    "aliases": [
-        {
-            "alias": "2.5",
-            "alias_normalized": "2.5.0.0",
-            "version": "9999999-dev",
-            "package": "symplify/easy-coding-standard"
-        },
-        {
-            "alias": "2.5",
-            "alias_normalized": "2.5.0.0",
-            "version": "9999999-dev",
-            "package": "symplify/coding-standard"
-        },
-        {
-            "alias": "2.5",
-            "alias_normalized": "2.5.0.0",
-            "version": "9999999-dev",
-            "package": "symplify/package-builder"
-        }
-    ],
+    "aliases": [],
     "minimum-stability": "stable",
     "stability-flags": {
-        "symplify/easy-coding-standard": 20,
-        "symplify/coding-standard": 20,
-        "symplify/package-builder": 20
+        "symplify/easy-coding-standard": 5,
+        "symplify/coding-standard": 5,
+        "symplify/package-builder": 5
     },
     "prefer-stable": false,
     "prefer-lowest": false,
diff --git a/docs/index.md b/docs/index.md
index ef3a0e9..f817b0a 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -17,11 +17,11 @@
 
 Fresh approach to Machine Learning in PHP. Algorithms, Cross Validation, Neural Network, Preprocessing, Feature Extraction and much more in one library.
 
-PHP-ML requires PHP >= 7.0.
+PHP-ML requires PHP >= 7.1.
 
 Simple example of classification:
 ```php
-require_once 'vendor/autoload.php';
+require_once __DIR__ . '/vendor/autoload.php';
 
 use Phpml\Classification\KNearestNeighbors;
 
@@ -54,57 +54,57 @@ Example scripts are available in a separate repository [php-ai/php-ml-examples](
 ## Features
 
 * Association rule Lerning
-    * [Apriori](machine-learning/association/apriori/)
+    * [Apriori](machine-learning/association/apriori.md)
 * Classification
-    * [SVC](machine-learning/classification/svc/)
-    * [k-Nearest Neighbors](machine-learning/classification/k-nearest-neighbors/)
-    * [Naive Bayes](machine-learning/classification/naive-bayes/)
+    * [SVC](machine-learning/classification/svc.md)
+    * [k-Nearest Neighbors](machine-learning/classification/k-nearest-neighbors.md)
+    * [Naive Bayes](machine-learning/classification/naive-bayes.md)
 * Regression
-    * [Least Squares](machine-learning/regression/least-squares/)
-    * [SVR](machine-learning/regression/svr/)
+    * [Least Squares](machine-learning/regression/least-squares.md)
+    * [SVR](machine-learning/regression/svr.md)
 * Clustering
-    * [k-Means](machine-learning/clustering/k-means/)
-    * [DBSCAN](machine-learning/clustering/dbscan/)
+    * [k-Means](machine-learning/clustering/k-means.md)
+    * [DBSCAN](machine-learning/clustering/dbscan.md)
 * Metric
-    * [Accuracy](machine-learning/metric/accuracy/)
-    * [Confusion Matrix](machine-learning/metric/confusion-matrix/)
-    * [Classification Report](machine-learning/metric/classification-report/)
+    * [Accuracy](machine-learning/metric/accuracy.md)
+    * [Confusion Matrix](machine-learning/metric/confusion-matrix.md)
+    * [Classification Report](machine-learning/metric/classification-report.md)
 * Workflow
     * [Pipeline](machine-learning/workflow/pipeline)
 * Neural Network
-    * [Multilayer Perceptron Classifier](machine-learning/neural-network/multilayer-perceptron-classifier/)
+    * [Multilayer Perceptron Classifier](machine-learning/neural-network/multilayer-perceptron-classifier.md)
 * Cross Validation
-    * [Random Split](machine-learning/cross-validation/random-split/)
-    * [Stratified Random Split](machine-learning/cross-validation/stratified-random-split/)
+    * [Random Split](machine-learning/cross-validation/random-split.md)
+    * [Stratified Random Split](machine-learning/cross-validation/stratified-random-split.md)
 * Preprocessing
-    * [Normalization](machine-learning/preprocessing/normalization/)
-    * [Imputation missing values](machine-learning/preprocessing/imputation-missing-values/)
+    * [Normalization](machine-learning/preprocessing/normalization.md)
+    * [Imputation missing values](machine-learning/preprocessing/imputation-missing-values.md)
 * Feature Extraction
-    * [Token Count Vectorizer](machine-learning/feature-extraction/token-count-vectorizer/)
-    * [Tf-idf Transformer](machine-learning/feature-extraction/tf-idf-transformer/)
+    * [Token Count Vectorizer](machine-learning/feature-extraction/token-count-vectorizer.md)
+    * [Tf-idf Transformer](machine-learning/feature-extraction/tf-idf-transformer.md)
 * Datasets
-    * [Array](machine-learning/datasets/array-dataset/)
-    * [CSV](machine-learning/datasets/csv-dataset/)
-    * [Files](machine-learning/datasets/files-dataset/)
+    * [Array](machine-learning/datasets/array-dataset.md)
+    * [CSV](machine-learning/datasets/csv-dataset.md)
+    * [Files](machine-learning/datasets/files-dataset.md)
     * Ready to use:
-        * [Iris](machine-learning/datasets/demo/iris/)
-        * [Wine](machine-learning/datasets/demo/wine/)
-        * [Glass](machine-learning/datasets/demo/glass/)
+        * [Iris](machine-learning/datasets/demo/iris.md)
+        * [Wine](machine-learning/datasets/demo/wine.md)
+        * [Glass](machine-learning/datasets/demo/glass.md)
 * Models management
-    * [Persistency](machine-learning/model-manager/persistency/)
+    * [Persistency](machine-learning/model-manager/persistency.md)
 * Math
-    * [Distance](math/distance/)
-    * [Matrix](math/matrix/)
-    * [Set](math/set/)
-    * [Statistic](math/statistic/)
+    * [Distance](math/distance.md)
+    * [Matrix](math/matrix.md)
+    * [Set](math/set.md)
+    * [Statistic](math/statistic.md)
     
 
 ## Contribute
 
-- Issue Tracker: github.com/php-ai/php-ml/issues
-- Source Code: github.com/php-ai/php-ml
+- Issue Tracker: [github.com/php-ai/php-ml/issues](https://github.com/php-ai/php-ml/issues)
+- Source Code: [github.com/php-ai/php-ml](https://github.com/php-ai/php-ml)
 
-You can find more about contributing in [CONTRIBUTING.md](CONTRIBUTING.md).
+You can find more about contributing in [CONTRIBUTING.md](../CONTRIBUTING.md).
 
 ## License
 
diff --git a/easy-coding-standard.neon b/easy-coding-standard.neon
index 14d8770..9155b10 100644
--- a/easy-coding-standard.neon
+++ b/easy-coding-standard.neon
@@ -11,6 +11,25 @@ includes:
     #- vendor/symplify/easy-coding-standard/config/common/strict.neon
 
 checkers:
+    # spacing
+    - PhpCsFixer\Fixer\PhpTag\BlankLineAfterOpeningTagFixer
+    - PhpCsFixer\Fixer\Whitespace\BlankLineBeforeStatementFixer
+    - PhpCsFixer\Fixer\CastNotation\CastSpacesFixer
+    PhpCsFixer\Fixer\Operator\ConcatSpaceFixer:
+        spacing: none
+    - PhpCsFixer\Fixer\ClassNotation\MethodSeparationFixer
+    - PhpCsFixer\Fixer\ClassNotation\NoBlankLinesAfterClassOpeningFixer
+    PhpCsFixer\Fixer\Whitespace\NoSpacesAroundOffsetFixer:
+        positions: ['inside', 'outside']
+    PhpCsFixer\Fixer\Operator\BinaryOperatorSpacesFixer:
+        align_double_arrow: false
+        align_equals: false
+
+    # phpdoc
+    - PhpCsFixer\Fixer\Phpdoc\PhpdocSeparationFixer
+    - PhpCsFixer\Fixer\Phpdoc\PhpdocAlignFixer
+
+    # Symplify
     - Symplify\CodingStandard\Fixer\Import\ImportNamespacedNameFixer
     - Symplify\CodingStandard\Fixer\Php\ClassStringToClassConstantFixer
     - Symplify\CodingStandard\Fixer\Property\ArrayPropertyDefaultValueFixer
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..19e3c20
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,19 @@
+parameters:
+    ignoreErrors:
+        - '#Phpml\\Dataset\\FilesDataset::__construct\(\) does not call parent constructor from Phpml\\Dataset\\ArrayDataset#'
+        - '#Parameter \#2 \$predictedLabels of static method Phpml\\Metric\\Accuracy::score\(\) expects mixed\[\], mixed\[\]\|string given#'
+
+        # should be always defined
+        - '#Undefined variable: \$j#'
+
+        # bugged
+        - '#expects [a-z\\\|\[\]]*, [a-z\\\|\(\)\[\]]*\[\] given#'
+
+        # mock
+        - '#Parameter \#1 \$node of class Phpml\\NeuralNetwork\\Node\\Neuron\\Synapse constructor expects Phpml\\NeuralNetwork\\Node, Phpml\\NeuralNetwork\\Node\\Neuron\|PHPUnit_Framework_MockObject_MockObject given#'
+        - '#Parameter \#1 \$(activationFunction|synapse) of class Phpml\\NeuralNetwork\\Node\\Neuron constructor expects Phpml\\NeuralNetwork\\ActivationFunction|null, Phpml\\NeuralNetwork\\ActivationFunction\\BinaryStep|PHPUnit_Framework_MockObject_MockObject given#'
+
+        # probably known value
+        - '#Method Phpml\\Classification\\DecisionTree::getBestSplit\(\) should return Phpml\\Classification\\DecisionTree\\DecisionTreeLeaf but returns Phpml\\Classification\\DecisionTree\\DecisionTreeLeaf\|null#'
+        - '#Method Phpml\\Classification\\Linear\\DecisionStump::getBestNumericalSplit\(\) should return mixed\[\] but returns \(float\|int\|mixed\|string\)\[\]\|null#'
+        - '#Method Phpml\\Classification\\Linear\\DecisionStump::getBestNominalSplit\(\) should return mixed\[\] but returns mixed\[\]\|null#'
diff --git a/src/Phpml/Association/Apriori.php b/src/Phpml/Association/Apriori.php
index e13f556..76d8624 100644
--- a/src/Phpml/Association/Apriori.php
+++ b/src/Phpml/Association/Apriori.php
@@ -244,6 +244,7 @@ class Apriori implements Associator
                 foreach ((array) $this->samples as $sample) {
                     if ($this->subset($sample, $candidate)) {
                         $candidates[] = $candidate;
+
                         continue 2;
                     }
                 }
diff --git a/src/Phpml/Classification/DecisionTree.php b/src/Phpml/Classification/DecisionTree.php
index 5bb730b..d660322 100644
--- a/src/Phpml/Classification/DecisionTree.php
+++ b/src/Phpml/Classification/DecisionTree.php
@@ -59,14 +59,14 @@ class DecisionTree implements Classifier
     private $selectedFeatures = [];
 
     /**
-     * @var array
+     * @var array|null
      */
-    private $featureImportances = null;
+    private $featureImportances;
 
     /**
-     * @var array
+     * @var array|null
      */
-    private $columnNames = null;
+    private $columnNames;
 
     public function __construct(int $maxDepth = 10)
     {
diff --git a/src/Phpml/Classification/DecisionTree/DecisionTreeLeaf.php b/src/Phpml/Classification/DecisionTree/DecisionTreeLeaf.php
index f3f9449..5164472 100644
--- a/src/Phpml/Classification/DecisionTree/DecisionTreeLeaf.php
+++ b/src/Phpml/Classification/DecisionTree/DecisionTreeLeaf.php
@@ -9,7 +9,7 @@ use Phpml\Math\Comparison;
 class DecisionTreeLeaf
 {
     /**
-     * @var string
+     * @var string|int
      */
     public $value;
 
@@ -52,7 +52,7 @@ class DecisionTreeLeaf
     public $classValue = '';
 
     /**
-     * @var bool
+     * @var bool|int
      */
     public $isTerminal = false;
 
diff --git a/src/Phpml/Classification/Ensemble/Bagging.php b/src/Phpml/Classification/Ensemble/Bagging.php
index 6fa1ec8..a3d8e5e 100644
--- a/src/Phpml/Classification/Ensemble/Bagging.php
+++ b/src/Phpml/Classification/Ensemble/Bagging.php
@@ -31,7 +31,7 @@ class Bagging implements Classifier
     protected $numClassifier;
 
     /**
-     * @var Classifier
+     * @var string
      */
     protected $classifier = DecisionTree::class;
 
diff --git a/src/Phpml/Classification/Linear/Adaline.php b/src/Phpml/Classification/Linear/Adaline.php
index cda746f..de2e152 100644
--- a/src/Phpml/Classification/Linear/Adaline.php
+++ b/src/Phpml/Classification/Linear/Adaline.php
@@ -21,7 +21,7 @@ class Adaline extends Perceptron
     /**
      * Training type may be either 'Batch' or 'Online' learning
      *
-     * @var string
+     * @var string|int
      */
     protected $trainingType;
 
diff --git a/src/Phpml/Classification/Linear/DecisionStump.php b/src/Phpml/Classification/Linear/DecisionStump.php
index 3f6eb58..439ea56 100644
--- a/src/Phpml/Classification/Linear/DecisionStump.php
+++ b/src/Phpml/Classification/Linear/DecisionStump.php
@@ -224,7 +224,7 @@ class DecisionStump extends WeightedClassifier
             foreach ($distinctVals as $val) {
                 [$errorRate, $prob] = $this->calculateErrorRate($targets, $val, $operator, $values);
 
-                if ($split == null || $split['trainingErrorRate'] < $errorRate) {
+                if ($split === null || $split['trainingErrorRate'] < $errorRate) {
                     $split = [
                         'value' => $val,
                         'operator' => $operator,
diff --git a/src/Phpml/Classification/Linear/LogisticRegression.php b/src/Phpml/Classification/Linear/LogisticRegression.php
index 3818161..b595587 100644
--- a/src/Phpml/Classification/Linear/LogisticRegression.php
+++ b/src/Phpml/Classification/Linear/LogisticRegression.php
@@ -119,19 +119,25 @@ class LogisticRegression extends Adaline
      *
      * @throws \Exception
      */
-    protected function runTraining(array $samples, array $targets)
+    protected function runTraining(array $samples, array $targets): void
     {
         $callback = $this->getCostFunction();
 
         switch ($this->trainingType) {
             case self::BATCH_TRAINING:
-                return $this->runGradientDescent($samples, $targets, $callback, true);
+                $this->runGradientDescent($samples, $targets, $callback, true);
+
+                return;
 
             case self::ONLINE_TRAINING:
-                return $this->runGradientDescent($samples, $targets, $callback, false);
+                $this->runGradientDescent($samples, $targets, $callback, false);
+
+                return;
 
             case self::CONJUGATE_GRAD_TRAINING:
-                return $this->runConjugateGradient($samples, $targets, $callback);
+                $this->runConjugateGradient($samples, $targets, $callback);
+
+                return;
 
             default:
                 throw new Exception('Logistic regression has invalid training type: %s.', $this->trainingType);
@@ -143,7 +149,7 @@ class LogisticRegression extends Adaline
      */
     protected function runConjugateGradient(array $samples, array $targets, Closure $gradientFunc): void
     {
-        if (empty($this->optimizer)) {
+        if ($this->optimizer === null) {
             $this->optimizer = (new ConjugateGradient($this->featureCount))
                 ->setMaxIterations($this->maxIterations);
         }
diff --git a/src/Phpml/Classification/Linear/Perceptron.php b/src/Phpml/Classification/Linear/Perceptron.php
index 0db7496..6838227 100644
--- a/src/Phpml/Classification/Linear/Perceptron.php
+++ b/src/Phpml/Classification/Linear/Perceptron.php
@@ -19,7 +19,7 @@ class Perceptron implements Classifier, IncrementalEstimator
     use Predictable, OneVsRest;
 
     /**
-     * @var \Phpml\Helper\Optimizer\Optimizer
+     * @var \Phpml\Helper\Optimizer\Optimizer|GD|StochasticGD|null
      */
     protected $optimizer;
 
@@ -34,7 +34,7 @@ class Perceptron implements Classifier, IncrementalEstimator
     protected $featureCount = 0;
 
     /**
-     * @var array
+     * @var array|null
      */
     protected $weights = [];
 
@@ -67,8 +67,8 @@ class Perceptron implements Classifier, IncrementalEstimator
      * Initalize a perceptron classifier with given learning rate and maximum
      * number of iterations used while training the perceptron
      *
-     * @param float $learningRate    Value between 0.0(exclusive) and 1.0(inclusive)
-     * @param int   $maxIterations   Must be at least 1
+     * @param float $learningRate  Value between 0.0(exclusive) and 1.0(inclusive)
+     * @param int   $maxIterations Must be at least 1
      *
      * @throws \Exception
      */
@@ -178,7 +178,7 @@ class Perceptron implements Classifier, IncrementalEstimator
     {
         $class = $isBatch ? GD::class : StochasticGD::class;
 
-        if (empty($this->optimizer)) {
+        if ($this->optimizer === null) {
             $this->optimizer = (new $class($this->featureCount))
                 ->setLearningRate($this->learningRate)
                 ->setMaxIterations($this->maxIterations)
diff --git a/src/Phpml/Clustering/KMeans/Point.php b/src/Phpml/Clustering/KMeans/Point.php
index 6aa40a9..8c918a7 100644
--- a/src/Phpml/Clustering/KMeans/Point.php
+++ b/src/Phpml/Clustering/KMeans/Point.php
@@ -48,12 +48,15 @@ class Point implements ArrayAccess
      */
     public function getClosest(array $points)
     {
+        $minPoint = null;
+
         foreach ($points as $point) {
             $distance = $this->getDistanceWith($point, false);
 
             if (!isset($minDistance)) {
                 $minDistance = $distance;
                 $minPoint = $point;
+
                 continue;
             }
 
diff --git a/src/Phpml/Clustering/KMeans/Space.php b/src/Phpml/Clustering/KMeans/Space.php
index 0d4adf5..371bbc3 100644
--- a/src/Phpml/Clustering/KMeans/Space.php
+++ b/src/Phpml/Clustering/KMeans/Space.php
@@ -45,7 +45,7 @@ class Space extends SplObjectStorage
     }
 
     /**
-     * @param null  $data
+     * @param null $data
      */
     public function addPoint(array $coordinates, $data = null): void
     {
@@ -124,10 +124,12 @@ class Space extends SplObjectStorage
         switch ($initMethod) {
             case KMeans::INIT_RANDOM:
                 $clusters = $this->initializeRandomClusters($clustersNumber);
+
                 break;
 
             case KMeans::INIT_KMEANS_PLUS_PLUS:
                 $clusters = $this->initializeKMPPClusters($clustersNumber);
+
                 break;
 
             default:
@@ -200,6 +202,7 @@ class Space extends SplObjectStorage
                 }
 
                 $clusters[] = new Cluster($this, $point->getCoordinates());
+
                 break;
             }
         }
diff --git a/src/Phpml/DimensionReduction/KernelPCA.php b/src/Phpml/DimensionReduction/KernelPCA.php
index 1981cb5..65bb324 100644
--- a/src/Phpml/DimensionReduction/KernelPCA.php
+++ b/src/Phpml/DimensionReduction/KernelPCA.php
@@ -30,7 +30,7 @@ class KernelPCA extends PCA
     /**
      * Gamma value used by the kernel
      *
-     * @var float
+     * @var float|null
      */
     protected $gamma;
 
diff --git a/src/Phpml/FeatureExtraction/TokenCountVectorizer.php b/src/Phpml/FeatureExtraction/TokenCountVectorizer.php
index e0bd402..e0d4e10 100644
--- a/src/Phpml/FeatureExtraction/TokenCountVectorizer.php
+++ b/src/Phpml/FeatureExtraction/TokenCountVectorizer.php
@@ -15,7 +15,7 @@ class TokenCountVectorizer implements Transformer
     private $tokenizer;
 
     /**
-     * @var StopWords
+     * @var StopWords|null
      */
     private $stopWords;
 
diff --git a/src/Phpml/Helper/OneVsRest.php b/src/Phpml/Helper/OneVsRest.php
index 4f661ba..1c0ca93 100644
--- a/src/Phpml/Helper/OneVsRest.php
+++ b/src/Phpml/Helper/OneVsRest.php
@@ -33,7 +33,7 @@ trait OneVsRest
         // Clears previous stuff.
         $this->reset();
 
-        $this->trainBylabel($samples, $targets);
+        $this->trainByLabel($samples, $targets);
     }
 
     /**
diff --git a/src/Phpml/Helper/Optimizer/GD.php b/src/Phpml/Helper/Optimizer/GD.php
index 4eadf28..11577c9 100644
--- a/src/Phpml/Helper/Optimizer/GD.php
+++ b/src/Phpml/Helper/Optimizer/GD.php
@@ -15,9 +15,9 @@ class GD extends StochasticGD
     /**
      * Number of samples given
      *
-     * @var int
+     * @var int|null
      */
-    protected $sampleCount = null;
+    protected $sampleCount;
 
     public function runOptimization(array $samples, array $targets, Closure $gradientCb): array
     {
diff --git a/src/Phpml/Helper/Optimizer/StochasticGD.php b/src/Phpml/Helper/Optimizer/StochasticGD.php
index 07ad216..18a5f0c 100644
--- a/src/Phpml/Helper/Optimizer/StochasticGD.php
+++ b/src/Phpml/Helper/Optimizer/StochasticGD.php
@@ -31,7 +31,7 @@ class StochasticGD extends Optimizer
      * Callback function to get the gradient and cost value
      * for a specific set of theta (ϴ) and a pair of sample & target
      *
-     * @var \Closure
+     * @var \Closure|null
      */
     protected $gradientCb = null;
 
@@ -144,7 +144,7 @@ class StochasticGD extends Optimizer
      * The cost function to minimize and the gradient of the function are to be
      * handled by the callback function provided as the third parameter of the method.
      */
-    public function runOptimization(array $samples, array $targets, Closure $gradientCb): array
+    public function runOptimization(array $samples, array $targets, Closure $gradientCb): ?array
     {
         $this->samples = $samples;
         $this->targets = $targets;
@@ -181,7 +181,7 @@ class StochasticGD extends Optimizer
 
         // Solution in the pocket is better than or equal to the last state
         // so, we use this solution
-        return $this->theta = $bestTheta;
+        return $this->theta = (array) $bestTheta;
     }
 
     /**
diff --git a/src/Phpml/Math/LinearAlgebra/EigenvalueDecomposition.php b/src/Phpml/Math/LinearAlgebra/EigenvalueDecomposition.php
index 4d7f662..1730309 100644
--- a/src/Phpml/Math/LinearAlgebra/EigenvalueDecomposition.php
+++ b/src/Phpml/Math/LinearAlgebra/EigenvalueDecomposition.php
@@ -88,6 +88,8 @@ class EigenvalueDecomposition
 
     private $cdivi;
 
+    private $A;
+
     /**
      *	Constructor: Check for symmetry, then construct the eigenvalue decomposition
      */
diff --git a/src/Phpml/Math/LinearAlgebra/LUDecomposition.php b/src/Phpml/Math/LinearAlgebra/LUDecomposition.php
index 6ebd8cb..151e2cc 100644
--- a/src/Phpml/Math/LinearAlgebra/LUDecomposition.php
+++ b/src/Phpml/Math/LinearAlgebra/LUDecomposition.php
@@ -212,9 +212,9 @@ class LUDecomposition
     /**
      * Is the matrix nonsingular?
      *
-     * @return true if U, and hence A, is nonsingular.
+     * @return bool true if U, and hence A, is nonsingular.
      */
-    public function isNonsingular()
+    public function isNonsingular(): bool
     {
         for ($j = 0; $j < $this->n; ++$j) {
             if ($this->LU[$j][$j] == 0) {
diff --git a/src/Phpml/Math/Set.php b/src/Phpml/Math/Set.php
index a67d5c2..dcb02e6 100644
--- a/src/Phpml/Math/Set.php
+++ b/src/Phpml/Math/Set.php
@@ -15,7 +15,7 @@ class Set implements IteratorAggregate
     private $elements = [];
 
     /**
-     * @param string[]|int[]|float[] $elements
+     * @param string[]|int[]|float[]|bool[] $elements
      */
     public function __construct(array $elements = [])
     {
@@ -83,7 +83,7 @@ class Set implements IteratorAggregate
     }
 
     /**
-     * @param string|int|float $element
+     * @param string|int|float|bool $element
      */
     public function add($element): self
     {
@@ -91,7 +91,7 @@ class Set implements IteratorAggregate
     }
 
     /**
-     * @param string[]|int[]|float[] $elements
+     * @param string[]|int[]|float[]|bool[] $elements
      */
     public function addAll(array $elements): self
     {
diff --git a/src/Phpml/Metric/ClassificationReport.php b/src/Phpml/Metric/ClassificationReport.php
index 0f27b06..0c3198f 100644
--- a/src/Phpml/Metric/ClassificationReport.php
+++ b/src/Phpml/Metric/ClassificationReport.php
@@ -91,6 +91,7 @@ class ClassificationReport
             $values = array_filter($this->{$metric});
             if (empty($values)) {
                 $this->average[$metric] = 0.0;
+
                 continue;
             }
 
diff --git a/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php b/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php
index 5ace597..1a997be 100644
--- a/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php
+++ b/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php
@@ -26,14 +26,14 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
     protected $classes = [];
 
     /**
-     * @var ActivationFunction
+     * @var ActivationFunction|null
      */
     protected $activationFunction;
 
     /**
      * @var Backpropagation
      */
-    protected $backpropagation = null;
+    protected $backpropagation;
 
     /**
      * @var int
@@ -50,6 +50,11 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
      */
     private $learningRate;
 
+    /**
+     * @var int
+     */
+    private $iterations;
+
     /**
      * @throws InvalidArgumentException
      */
diff --git a/src/Phpml/NeuralNetwork/Node/Neuron.php b/src/Phpml/NeuralNetwork/Node/Neuron.php
index a6c10e6..2dff600 100644
--- a/src/Phpml/NeuralNetwork/Node/Neuron.php
+++ b/src/Phpml/NeuralNetwork/Node/Neuron.php
@@ -24,13 +24,11 @@ class Neuron implements Node
     /**
      * @var float
      */
-    protected $output;
+    protected $output = 0.0;
 
     public function __construct(?ActivationFunction $activationFunction = null)
     {
         $this->activationFunction = $activationFunction ?: new Sigmoid();
-        $this->synapses = [];
-        $this->output = 0;
     }
 
     public function addSynapse(Synapse $synapse): void
@@ -48,8 +46,8 @@ class Neuron implements Node
 
     public function getOutput(): float
     {
-        if ($this->output === 0) {
-            $sum = 0;
+        if ($this->output === 0.0) {
+            $sum = 0.0;
             foreach ($this->synapses as $synapse) {
                 $sum += $synapse->getOutput();
             }
@@ -62,6 +60,6 @@ class Neuron implements Node
 
     public function reset(): void
     {
-        $this->output = 0;
+        $this->output = 0.0;
     }
 }
diff --git a/src/Phpml/NeuralNetwork/Training/Backpropagation.php b/src/Phpml/NeuralNetwork/Training/Backpropagation.php
index df515b2..4144c30 100644
--- a/src/Phpml/NeuralNetwork/Training/Backpropagation.php
+++ b/src/Phpml/NeuralNetwork/Training/Backpropagation.php
@@ -15,14 +15,14 @@ class Backpropagation
     private $learningRate;
 
     /**
-     * @var array
+     * @var array|null
      */
-    private $sigmas = null;
+    private $sigmas;
 
     /**
-     * @var array
+     * @var array|null
      */
-    private $prevSigmas = null;
+    private $prevSigmas;
 
     public function __construct(float $learningRate)
     {
diff --git a/src/Phpml/Preprocessing/Imputer.php b/src/Phpml/Preprocessing/Imputer.php
index fdf8796..593756c 100644
--- a/src/Phpml/Preprocessing/Imputer.php
+++ b/src/Phpml/Preprocessing/Imputer.php
@@ -33,8 +33,7 @@ class Imputer implements Preprocessor
     private $samples = [];
 
     /**
-     * @param mixed      $missingValue
-     * @param array|null $samples
+     * @param mixed $missingValue
      */
     public function __construct($missingValue, Strategy $strategy, int $axis = self::AXIS_COLUMN, array $samples = [])
     {
diff --git a/src/Phpml/SupportVectorMachine/DataTransformer.php b/src/Phpml/SupportVectorMachine/DataTransformer.php
index 2ce938e..6516cbf 100644
--- a/src/Phpml/SupportVectorMachine/DataTransformer.php
+++ b/src/Phpml/SupportVectorMachine/DataTransformer.php
@@ -9,6 +9,8 @@ class DataTransformer
     public static function trainingSet(array $samples, array $labels, bool $targets = false): string
     {
         $set = '';
+        $numericLabels = [];
+
         if (!$targets) {
             $numericLabels = self::numericLabels($labels);
         }
diff --git a/src/Phpml/SupportVectorMachine/SupportVectorMachine.php b/src/Phpml/SupportVectorMachine/SupportVectorMachine.php
index 2415eda..4565332 100644
--- a/src/Phpml/SupportVectorMachine/SupportVectorMachine.php
+++ b/src/Phpml/SupportVectorMachine/SupportVectorMachine.php
@@ -37,7 +37,7 @@ class SupportVectorMachine
     private $degree;
 
     /**
-     * @var float
+     * @var float|null
      */
     private $gamma;
 
diff --git a/tests/Phpml/Association/AprioriTest.php b/tests/Phpml/Association/AprioriTest.php
index 68456ff..8b95237 100644
--- a/tests/Phpml/Association/AprioriTest.php
+++ b/tests/Phpml/Association/AprioriTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification;
+namespace Phpml\Tests\Association;
 
 use Phpml\Association\Apriori;
 use Phpml\ModelManager;
@@ -173,8 +173,8 @@ class AprioriTest extends TestCase
     /**
      * Invokes objects method. Private/protected will be set accessible.
      *
-     * @param string $method  Method name to be called
-     * @param array  $params  Array of params to be passed
+     * @param string $method Method name to be called
+     * @param array  $params Array of params to be passed
      *
      * @return mixed
      */
diff --git a/tests/Phpml/Classification/DecisionTree/DecisionTreeLeafTest.php b/tests/Phpml/Classification/DecisionTree/DecisionTreeLeafTest.php
index 626ed64..abcf10d 100644
--- a/tests/Phpml/Classification/DecisionTree/DecisionTreeLeafTest.php
+++ b/tests/Phpml/Classification/DecisionTree/DecisionTreeLeafTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification\DecisionTree;
+namespace Phpml\Tests\Classification\DecisionTree;
 
 use Phpml\Classification\DecisionTree\DecisionTreeLeaf;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Classification/DecisionTreeTest.php b/tests/Phpml/Classification/DecisionTreeTest.php
index 8533500..9478a2a 100644
--- a/tests/Phpml/Classification/DecisionTreeTest.php
+++ b/tests/Phpml/Classification/DecisionTreeTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification;
+namespace Phpml\Tests\Classification;
 
 use Phpml\Classification\DecisionTree;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/Classification/Ensemble/AdaBoostTest.php b/tests/Phpml/Classification/Ensemble/AdaBoostTest.php
index e01066c..7677c31 100644
--- a/tests/Phpml/Classification/Ensemble/AdaBoostTest.php
+++ b/tests/Phpml/Classification/Ensemble/AdaBoostTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification\Ensemble;
+namespace Phpml\Tests\Classification\Ensemble;
 
 use Phpml\Classification\Ensemble\AdaBoost;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/Classification/Ensemble/BaggingTest.php b/tests/Phpml/Classification/Ensemble/BaggingTest.php
index 175b79a..69c4d01 100644
--- a/tests/Phpml/Classification/Ensemble/BaggingTest.php
+++ b/tests/Phpml/Classification/Ensemble/BaggingTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification\Ensemble;
+namespace Phpml\Tests\Classification\Ensemble;
 
 use Phpml\Classification\DecisionTree;
 use Phpml\Classification\Ensemble\Bagging;
diff --git a/tests/Phpml/Classification/Ensemble/RandomForestTest.php b/tests/Phpml/Classification/Ensemble/RandomForestTest.php
index f2871e3..ea0cce1 100644
--- a/tests/Phpml/Classification/Ensemble/RandomForestTest.php
+++ b/tests/Phpml/Classification/Ensemble/RandomForestTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification\Ensemble;
+namespace Phpml\Tests\Classification\Ensemble;
 
 use Phpml\Classification\DecisionTree;
 use Phpml\Classification\Ensemble\RandomForest;
@@ -21,6 +21,7 @@ class RandomForestTest extends BaggingTest
             $this->assertEquals(1, 1);
         }
     }
+
     protected function getClassifier($numBaseClassifiers = 50)
     {
         $classifier = new RandomForest($numBaseClassifiers);
diff --git a/tests/Phpml/Classification/KNearestNeighborsTest.php b/tests/Phpml/Classification/KNearestNeighborsTest.php
index d9114b5..d96152a 100644
--- a/tests/Phpml/Classification/KNearestNeighborsTest.php
+++ b/tests/Phpml/Classification/KNearestNeighborsTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification;
+namespace Phpml\Tests\Classification;
 
 use Phpml\Classification\KNearestNeighbors;
 use Phpml\Math\Distance\Chebyshev;
diff --git a/tests/Phpml/Classification/Linear/AdalineTest.php b/tests/Phpml/Classification/Linear/AdalineTest.php
index 0a90a18..c8ca752 100644
--- a/tests/Phpml/Classification/Linear/AdalineTest.php
+++ b/tests/Phpml/Classification/Linear/AdalineTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification\Linear;
+namespace Phpml\Tests\Classification\Linear;
 
 use Phpml\Classification\Linear\Adaline;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/Classification/Linear/DecisionStumpTest.php b/tests/Phpml/Classification/Linear/DecisionStumpTest.php
index 7fbabec..93c8595 100644
--- a/tests/Phpml/Classification/Linear/DecisionStumpTest.php
+++ b/tests/Phpml/Classification/Linear/DecisionStumpTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification\Linear;
+namespace Phpml\Tests\Classification\Linear;
 
 use Phpml\Classification\Linear\DecisionStump;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/Classification/Linear/PerceptronTest.php b/tests/Phpml/Classification/Linear/PerceptronTest.php
index 17b1db8..35af855 100644
--- a/tests/Phpml/Classification/Linear/PerceptronTest.php
+++ b/tests/Phpml/Classification/Linear/PerceptronTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification\Linear;
+namespace Phpml\Tests\Classification\Linear;
 
 use Phpml\Classification\Linear\Perceptron;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/Classification/MLPClassifierTest.php b/tests/Phpml/Classification/MLPClassifierTest.php
index ef62d06..ef40618 100644
--- a/tests/Phpml/Classification/MLPClassifierTest.php
+++ b/tests/Phpml/Classification/MLPClassifierTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification;
+namespace Phpml\Tests\Classification;
 
 use Phpml\Classification\MLPClassifier;
 use Phpml\Exception\InvalidArgumentException;
diff --git a/tests/Phpml/Classification/NaiveBayesTest.php b/tests/Phpml/Classification/NaiveBayesTest.php
index c423c6d..8312e9c 100644
--- a/tests/Phpml/Classification/NaiveBayesTest.php
+++ b/tests/Phpml/Classification/NaiveBayesTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification;
+namespace Phpml\Tests\Classification;
 
 use Phpml\Classification\NaiveBayes;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/Classification/SVCTest.php b/tests/Phpml/Classification/SVCTest.php
index 0941b34..0709e04 100644
--- a/tests/Phpml/Classification/SVCTest.php
+++ b/tests/Phpml/Classification/SVCTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Classification;
+namespace Phpml\Tests\Classification;
 
 use Phpml\Classification\SVC;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/Clustering/DBSCANTest.php b/tests/Phpml/Clustering/DBSCANTest.php
index f12fb03..c0d0401 100644
--- a/tests/Phpml/Clustering/DBSCANTest.php
+++ b/tests/Phpml/Clustering/DBSCANTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Clustering;
+namespace Phpml\Tests\Clustering;
 
 use Phpml\Clustering\DBSCAN;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Clustering/FuzzyCMeansTest.php b/tests/Phpml/Clustering/FuzzyCMeansTest.php
index 7b19422..1c3af15 100644
--- a/tests/Phpml/Clustering/FuzzyCMeansTest.php
+++ b/tests/Phpml/Clustering/FuzzyCMeansTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Clustering;
+namespace Phpml\Tests\Clustering;
 
 use Phpml\Clustering\FuzzyCMeans;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Clustering/KMeansTest.php b/tests/Phpml/Clustering/KMeansTest.php
index d212157..dedf981 100644
--- a/tests/Phpml/Clustering/KMeansTest.php
+++ b/tests/Phpml/Clustering/KMeansTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Clustering;
+namespace Phpml\Tests\Clustering;
 
 use Phpml\Clustering\KMeans;
 use Phpml\Exception\InvalidArgumentException;
diff --git a/tests/Phpml/CrossValidation/RandomSplitTest.php b/tests/Phpml/CrossValidation/RandomSplitTest.php
index 8058fd6..75f60ff 100644
--- a/tests/Phpml/CrossValidation/RandomSplitTest.php
+++ b/tests/Phpml/CrossValidation/RandomSplitTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\CrossValidation;
+namespace Phpml\Tests\CrossValidation;
 
 use Phpml\CrossValidation\RandomSplit;
 use Phpml\Dataset\ArrayDataset;
diff --git a/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php b/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php
index e953ca7..5309dc6 100644
--- a/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php
+++ b/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\CrossValidation;
+namespace Phpml\Tests\CrossValidation;
 
 use Phpml\CrossValidation\StratifiedRandomSplit;
 use Phpml\Dataset\ArrayDataset;
diff --git a/tests/Phpml/Dataset/ArrayDatasetTest.php b/tests/Phpml/Dataset/ArrayDatasetTest.php
index e0a6b91..bca9e43 100644
--- a/tests/Phpml/Dataset/ArrayDatasetTest.php
+++ b/tests/Phpml/Dataset/ArrayDatasetTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Dataset;
+namespace Phpml\Tests\Dataset;
 
 use Phpml\Dataset\ArrayDataset;
 use Phpml\Exception\InvalidArgumentException;
diff --git a/tests/Phpml/Dataset/CsvDatasetTest.php b/tests/Phpml/Dataset/CsvDatasetTest.php
index 5049253..90eb1d0 100644
--- a/tests/Phpml/Dataset/CsvDatasetTest.php
+++ b/tests/Phpml/Dataset/CsvDatasetTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Dataset;
+namespace Phpml\Tests\Dataset;
 
 use Phpml\Dataset\CsvDataset;
 use Phpml\Exception\FileException;
diff --git a/tests/Phpml/Dataset/Demo/GlassDatasetTest.php b/tests/Phpml/Dataset/Demo/GlassDatasetTest.php
index 8feef45..0d873e6 100644
--- a/tests/Phpml/Dataset/Demo/GlassDatasetTest.php
+++ b/tests/Phpml/Dataset/Demo/GlassDatasetTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Dataset\Demo;
+namespace Phpml\Tests\Dataset\Demo;
 
 use Phpml\Dataset\Demo\GlassDataset;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Dataset/Demo/IrisDatasetTest.php b/tests/Phpml/Dataset/Demo/IrisDatasetTest.php
index faa48c6..4fb2ee2 100644
--- a/tests/Phpml/Dataset/Demo/IrisDatasetTest.php
+++ b/tests/Phpml/Dataset/Demo/IrisDatasetTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Dataset\Demo;
+namespace Phpml\Tests\Dataset\Demo;
 
 use Phpml\Dataset\Demo\IrisDataset;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Dataset/Demo/WineDatasetTest.php b/tests/Phpml/Dataset/Demo/WineDatasetTest.php
index e0324b4..1b7a982 100644
--- a/tests/Phpml/Dataset/Demo/WineDatasetTest.php
+++ b/tests/Phpml/Dataset/Demo/WineDatasetTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Dataset\Demo;
+namespace Phpml\Tests\Dataset\Demo;
 
 use Phpml\Dataset\Demo\WineDataset;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Dataset/FilesDatasetTest.php b/tests/Phpml/Dataset/FilesDatasetTest.php
index ee08395..08b568d 100644
--- a/tests/Phpml/Dataset/FilesDatasetTest.php
+++ b/tests/Phpml/Dataset/FilesDatasetTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Dataset;
+namespace Phpml\Tests\Dataset;
 
 use Phpml\Dataset\FilesDataset;
 use Phpml\Exception\DatasetException;
diff --git a/tests/Phpml/DimensionReduction/KernelPCATest.php b/tests/Phpml/DimensionReduction/KernelPCATest.php
index 3f37e3c..05a4138 100644
--- a/tests/Phpml/DimensionReduction/KernelPCATest.php
+++ b/tests/Phpml/DimensionReduction/KernelPCATest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\DimensionReduction;
+namespace Phpml\Tests\DimensionReduction;
 
 use Phpml\DimensionReduction\KernelPCA;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/DimensionReduction/LDATest.php b/tests/Phpml/DimensionReduction/LDATest.php
index 42a0283..2803a4b 100644
--- a/tests/Phpml/DimensionReduction/LDATest.php
+++ b/tests/Phpml/DimensionReduction/LDATest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\DimensionReduction;
+namespace Phpml\Tests\DimensionReduction;
 
 use Phpml\Dataset\Demo\IrisDataset;
 use Phpml\DimensionReduction\LDA;
diff --git a/tests/Phpml/DimensionReduction/PCATest.php b/tests/Phpml/DimensionReduction/PCATest.php
index 38b4744..337b253 100644
--- a/tests/Phpml/DimensionReduction/PCATest.php
+++ b/tests/Phpml/DimensionReduction/PCATest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\DimensionReduction;
+namespace Phpml\Tests\DimensionReduction;
 
 use Phpml\DimensionReduction\PCA;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/FeatureExtraction/StopWordsTest.php b/tests/Phpml/FeatureExtraction/StopWordsTest.php
index 6d97a23..5780c39 100644
--- a/tests/Phpml/FeatureExtraction/StopWordsTest.php
+++ b/tests/Phpml/FeatureExtraction/StopWordsTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\FeatureExtraction;
+namespace Phpml\Tests\FeatureExtraction;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\FeatureExtraction\StopWords;
diff --git a/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php b/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php
index a8faacb..30bc0e5 100644
--- a/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php
+++ b/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\FeatureExtraction;
+namespace Phpml\Tests\FeatureExtraction;
 
 use Phpml\FeatureExtraction\TfIdfTransformer;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php b/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php
index 463570c..aaba5fc 100644
--- a/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php
+++ b/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\FeatureExtraction;
+namespace Phpml\Tests\FeatureExtraction;
 
 use Phpml\FeatureExtraction\StopWords;
 use Phpml\FeatureExtraction\TokenCountVectorizer;
diff --git a/tests/Phpml/Math/ComparisonTest.php b/tests/Phpml/Math/ComparisonTest.php
index ecb58c2..0118ee4 100644
--- a/tests/Phpml/Math/ComparisonTest.php
+++ b/tests/Phpml/Math/ComparisonTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Math;
+namespace Phpml\Tests\Math;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Comparison;
@@ -11,8 +11,8 @@ use PHPUnit\Framework\TestCase;
 class ComparisonTest extends TestCase
 {
     /**
-     * @param mixed  $a
-     * @param mixed  $b
+     * @param mixed $a
+     * @param mixed $b
      *
      * @dataProvider provideData
      */
diff --git a/tests/Phpml/Math/Distance/ChebyshevTest.php b/tests/Phpml/Math/Distance/ChebyshevTest.php
index 56d6685..262927b 100644
--- a/tests/Phpml/Math/Distance/ChebyshevTest.php
+++ b/tests/Phpml/Math/Distance/ChebyshevTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Metric;
+namespace Phpml\Tests\Math\Distance;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Distance\Chebyshev;
diff --git a/tests/Phpml/Math/Distance/EuclideanTest.php b/tests/Phpml/Math/Distance/EuclideanTest.php
index 4acb3d4..734bbd2 100644
--- a/tests/Phpml/Math/Distance/EuclideanTest.php
+++ b/tests/Phpml/Math/Distance/EuclideanTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Metric;
+namespace Phpml\Tests\Math\Distance;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Distance\Euclidean;
diff --git a/tests/Phpml/Math/Distance/ManhattanTest.php b/tests/Phpml/Math/Distance/ManhattanTest.php
index 2a05874..2eb9f06 100644
--- a/tests/Phpml/Math/Distance/ManhattanTest.php
+++ b/tests/Phpml/Math/Distance/ManhattanTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Metric;
+namespace Phpml\Tests\Math\Distance;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Distance\Manhattan;
diff --git a/tests/Phpml/Math/Distance/MinkowskiTest.php b/tests/Phpml/Math/Distance/MinkowskiTest.php
index a8159d7..6c7b897 100644
--- a/tests/Phpml/Math/Distance/MinkowskiTest.php
+++ b/tests/Phpml/Math/Distance/MinkowskiTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Metric;
+namespace Phpml\Tests\Math\Distance;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Distance\Minkowski;
diff --git a/tests/Phpml/Math/Kernel/RBFTest.php b/tests/Phpml/Math/Kernel/RBFTest.php
index 3ed7017..08f795d 100644
--- a/tests/Phpml/Math/Kernel/RBFTest.php
+++ b/tests/Phpml/Math/Kernel/RBFTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace test\Phpml\Math\Kernel;
+namespace Phpml\Tests\Math\Kernel;
 
 use Phpml\Math\Kernel\RBF;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Math/LinearAlgebra/EigenDecompositionTest.php b/tests/Phpml/Math/LinearAlgebra/EigenDecompositionTest.php
index 3956830..47c4798 100644
--- a/tests/Phpml/Math/LinearAlgebra/EigenDecompositionTest.php
+++ b/tests/Phpml/Math/LinearAlgebra/EigenDecompositionTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Math\LinearAlgebra;
+namespace Phpml\Tests\Math\LinearAlgebra;
 
 use Phpml\Math\LinearAlgebra\EigenvalueDecomposition;
 use Phpml\Math\Matrix;
diff --git a/tests/Phpml/Math/MatrixTest.php b/tests/Phpml/Math/MatrixTest.php
index fce83bf..da535bf 100644
--- a/tests/Phpml/Math/MatrixTest.php
+++ b/tests/Phpml/Math/MatrixTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Math;
+namespace Phpml\Tests\Math;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Exception\MatrixException;
diff --git a/tests/Phpml/Math/ProductTest.php b/tests/Phpml/Math/ProductTest.php
index bd55d11..da7450b 100644
--- a/tests/Phpml/Math/ProductTest.php
+++ b/tests/Phpml/Math/ProductTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Math;
+namespace Phpml\Tests\Math;
 
 use Phpml\Math\Product;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Math/SetTest.php b/tests/Phpml/Math/SetTest.php
index 645e607..2335c73 100644
--- a/tests/Phpml/Math/SetTest.php
+++ b/tests/Phpml/Math/SetTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Math;
+namespace Phpml\Tests\Math;
 
 use Phpml\Math\Set;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Math/Statistic/CorrelationTest.php b/tests/Phpml/Math/Statistic/CorrelationTest.php
index c091bb2..eebb065 100644
--- a/tests/Phpml/Math/Statistic/CorrelationTest.php
+++ b/tests/Phpml/Math/Statistic/CorrelationTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace test\Phpml\Math\StandardDeviation;
+namespace Phpml\Tests\Math\Statistic;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Statistic\Correlation;
diff --git a/tests/Phpml/Math/Statistic/CovarianceTest.php b/tests/Phpml/Math/Statistic/CovarianceTest.php
index 97ec194..2b64854 100644
--- a/tests/Phpml/Math/Statistic/CovarianceTest.php
+++ b/tests/Phpml/Math/Statistic/CovarianceTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Math\Statistic;
+namespace Phpml\Tests\Math\Statistic;
 
 use Phpml\Math\Statistic\Covariance;
 use Phpml\Math\Statistic\Mean;
diff --git a/tests/Phpml/Math/Statistic/GaussianTest.php b/tests/Phpml/Math/Statistic/GaussianTest.php
index 8030f85..e4627f4 100644
--- a/tests/Phpml/Math/Statistic/GaussianTest.php
+++ b/tests/Phpml/Math/Statistic/GaussianTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace test\Phpml\Math\StandardDeviation;
+namespace Phpml\Tests\Math\Statistic;
 
 use Phpml\Math\Statistic\Gaussian;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Math/Statistic/MeanTest.php b/tests/Phpml/Math/Statistic/MeanTest.php
index f19479a..3b98032 100644
--- a/tests/Phpml/Math/Statistic/MeanTest.php
+++ b/tests/Phpml/Math/Statistic/MeanTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace test\Phpml\Math\StandardDeviation;
+namespace Phpml\Tests\Math\Statistic;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Statistic\Mean;
diff --git a/tests/Phpml/Math/Statistic/StandardDeviationTest.php b/tests/Phpml/Math/Statistic/StandardDeviationTest.php
index 4bc4392..8333740 100644
--- a/tests/Phpml/Math/Statistic/StandardDeviationTest.php
+++ b/tests/Phpml/Math/Statistic/StandardDeviationTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace test\Phpml\Math\StandardDeviation;
+namespace Phpml\Tests\Math\Statistic;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Statistic\StandardDeviation;
diff --git a/tests/Phpml/Metric/AccuracyTest.php b/tests/Phpml/Metric/AccuracyTest.php
index e876da1..08d1c44 100644
--- a/tests/Phpml/Metric/AccuracyTest.php
+++ b/tests/Phpml/Metric/AccuracyTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Metric;
+namespace Phpml\Tests\Metric;
 
 use Phpml\Classification\SVC;
 use Phpml\CrossValidation\RandomSplit;
diff --git a/tests/Phpml/Metric/ClassificationReportTest.php b/tests/Phpml/Metric/ClassificationReportTest.php
index fb3471a..483f769 100644
--- a/tests/Phpml/Metric/ClassificationReportTest.php
+++ b/tests/Phpml/Metric/ClassificationReportTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Metric;
+namespace Phpml\Tests\Metric;
 
 use Phpml\Metric\ClassificationReport;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Metric/ConfusionMatrixTest.php b/tests/Phpml/Metric/ConfusionMatrixTest.php
index f958bdf..590aff8 100644
--- a/tests/Phpml/Metric/ConfusionMatrixTest.php
+++ b/tests/Phpml/Metric/ConfusionMatrixTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Metric;
+namespace Phpml\Tests\Metric;
 
 use Phpml\Metric\ConfusionMatrix;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/ModelManagerTest.php b/tests/Phpml/ModelManagerTest.php
index f47efb7..48ab747 100644
--- a/tests/Phpml/ModelManagerTest.php
+++ b/tests/Phpml/ModelManagerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests;
+namespace Phpml\Tests;
 
 use Phpml\Exception\FileException;
 use Phpml\ModelManager;
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php
index 91fc1c7..acc7977 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\ActivationFunction;
+namespace Phpml\Tests\NeuralNetwork\ActivationFunction;
 
 use Phpml\NeuralNetwork\ActivationFunction\BinaryStep;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php
index 58b4b87..2b08793 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\ActivationFunction;
+namespace Phpml\Tests\NeuralNetwork\ActivationFunction;
 
 use Phpml\NeuralNetwork\ActivationFunction\Gaussian;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php
index 00348d9..91e7eba 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\ActivationFunction;
+namespace Phpml\Tests\NeuralNetwork\ActivationFunction;
 
 use Phpml\NeuralNetwork\ActivationFunction\HyperbolicTangent;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/PReLUTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/PReLUTest.php
index 7e8e718..f407060 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/PReLUTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/PReLUTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\ActivationFunction;
+namespace Phpml\Tests\NeuralNetwork\ActivationFunction;
 
 use Phpml\NeuralNetwork\ActivationFunction\PReLU;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php
index d5a0ea3..30b50f8 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\ActivationFunction;
+namespace Phpml\Tests\NeuralNetwork\ActivationFunction;
 
 use Phpml\NeuralNetwork\ActivationFunction\Sigmoid;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/ThresholdedReLUTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/ThresholdedReLUTest.php
index 19a0312..f46ff02 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/ThresholdedReLUTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/ThresholdedReLUTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\ActivationFunction;
+namespace Phpml\Tests\NeuralNetwork\ActivationFunction;
 
 use Phpml\NeuralNetwork\ActivationFunction\ThresholdedReLU;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/LayerTest.php b/tests/Phpml/NeuralNetwork/LayerTest.php
index 11f5e6a..baa3f9a 100644
--- a/tests/Phpml/NeuralNetwork/LayerTest.php
+++ b/tests/Phpml/NeuralNetwork/LayerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork;
+namespace Phpml\Tests\NeuralNetwork;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\NeuralNetwork\Layer;
diff --git a/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php b/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php
index c1779b8..21f5e9c 100644
--- a/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php
+++ b/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php
@@ -2,12 +2,13 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\Network;
+namespace Phpml\Tests\NeuralNetwork\Network;
 
 use Phpml\NeuralNetwork\Layer;
 use Phpml\NeuralNetwork\Network\LayeredNetwork;
 use Phpml\NeuralNetwork\Node\Input;
 use PHPUnit\Framework\TestCase;
+use PHPUnit_Framework_MockObject_MockObject;
 
 class LayeredNetworkTest extends TestCase
 {
@@ -44,7 +45,10 @@ class LayeredNetworkTest extends TestCase
         $this->assertEquals([0.5], $network->getOutput());
     }
 
-    private function getLayeredNetworkMock(): LayeredNetwork
+    /**
+     * @return LayeredNetwork|PHPUnit_Framework_MockObject_MockObject
+     */
+    private function getLayeredNetworkMock()
     {
         return $this->getMockForAbstractClass(LayeredNetwork::class);
     }
diff --git a/tests/Phpml/NeuralNetwork/Node/BiasTest.php b/tests/Phpml/NeuralNetwork/Node/BiasTest.php
index ee311f5..e42a737 100644
--- a/tests/Phpml/NeuralNetwork/Node/BiasTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/BiasTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\Node;
+namespace Phpml\Tests\NeuralNetwork\Node;
 
 use Phpml\NeuralNetwork\Node\Bias;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/Node/InputTest.php b/tests/Phpml/NeuralNetwork/Node/InputTest.php
index 2d3be71..09ca831 100644
--- a/tests/Phpml/NeuralNetwork/Node/InputTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/InputTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\Node;
+namespace Phpml\Tests\NeuralNetwork\Node;
 
 use Phpml\NeuralNetwork\Node\Input;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php b/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php
index 1c09eae..973d216 100644
--- a/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\Node\Neuron;
+namespace Phpml\Tests\NeuralNetwork\Node\Neuron;
 
 use Phpml\NeuralNetwork\Node\Neuron;
 use Phpml\NeuralNetwork\Node\Neuron\Synapse;
@@ -41,8 +41,10 @@ class SynapseTest extends TestCase
 
     /**
      * @param int|float $output
+     *
+     * @return Neuron|PHPUnit_Framework_MockObject_MockObject
      */
-    private function getNodeMock($output = 1): PHPUnit_Framework_MockObject_MockObject
+    private function getNodeMock($output = 1)
     {
         $node = $this->getMockBuilder(Neuron::class)->getMock();
         $node->method('getOutput')->willReturn($output);
diff --git a/tests/Phpml/NeuralNetwork/Node/NeuronTest.php b/tests/Phpml/NeuralNetwork/Node/NeuronTest.php
index a58f2ec..03e309d 100644
--- a/tests/Phpml/NeuralNetwork/Node/NeuronTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/NeuronTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\NeuralNetwork\Node;
+namespace Phpml\Tests\NeuralNetwork\Node;
 
 use Phpml\NeuralNetwork\ActivationFunction\BinaryStep;
 use Phpml\NeuralNetwork\Node\Neuron;
@@ -22,6 +22,7 @@ class NeuronTest extends TestCase
 
     public function testNeuronActivationFunction(): void
     {
+        /** @var BinaryStep|PHPUnit_Framework_MockObject_MockObject $activationFunction */
         $activationFunction = $this->getMockBuilder(BinaryStep::class)->getMock();
         $activationFunction->method('compute')->with(0)->willReturn($output = 0.69);
 
diff --git a/tests/Phpml/PipelineTest.php b/tests/Phpml/PipelineTest.php
index caf1961..e45675d 100644
--- a/tests/Phpml/PipelineTest.php
+++ b/tests/Phpml/PipelineTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests;
+namespace Phpml\Tests;
 
 use Phpml\Classification\SVC;
 use Phpml\FeatureExtraction\TfIdfTransformer;
diff --git a/tests/Phpml/Preprocessing/ImputerTest.php b/tests/Phpml/Preprocessing/ImputerTest.php
index 658b454..c229c15 100644
--- a/tests/Phpml/Preprocessing/ImputerTest.php
+++ b/tests/Phpml/Preprocessing/ImputerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Preprocessing;
+namespace Phpml\Tests\Preprocessing;
 
 use Phpml\Preprocessing\Imputer;
 use Phpml\Preprocessing\Imputer\Strategy\MeanStrategy;
diff --git a/tests/Phpml/Preprocessing/NormalizerTest.php b/tests/Phpml/Preprocessing/NormalizerTest.php
index 5dfc207..ea762da 100644
--- a/tests/Phpml/Preprocessing/NormalizerTest.php
+++ b/tests/Phpml/Preprocessing/NormalizerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Preprocessing;
+namespace Phpml\Tests\Preprocessing;
 
 use Phpml\Exception\NormalizerException;
 use Phpml\Preprocessing\Normalizer;
diff --git a/tests/Phpml/Regression/LeastSquaresTest.php b/tests/Phpml/Regression/LeastSquaresTest.php
index 7517a9b..71215bc 100644
--- a/tests/Phpml/Regression/LeastSquaresTest.php
+++ b/tests/Phpml/Regression/LeastSquaresTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Regression;
+namespace Phpml\Tests\Regression;
 
 use Phpml\ModelManager;
 use Phpml\Regression\LeastSquares;
diff --git a/tests/Phpml/Regression/SVRTest.php b/tests/Phpml/Regression/SVRTest.php
index a220d21..d2fdefb 100644
--- a/tests/Phpml/Regression/SVRTest.php
+++ b/tests/Phpml/Regression/SVRTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Regression;
+namespace Phpml\Tests\Regression;
 
 use Phpml\ModelManager;
 use Phpml\Regression\SVR;
diff --git a/tests/Phpml/SupportVectorMachine/DataTransformerTest.php b/tests/Phpml/SupportVectorMachine/DataTransformerTest.php
index b1f8522..1db1fdf 100644
--- a/tests/Phpml/SupportVectorMachine/DataTransformerTest.php
+++ b/tests/Phpml/SupportVectorMachine/DataTransformerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\SupportVectorMachine;
+namespace Phpml\Tests\SupportVectorMachine;
 
 use Phpml\SupportVectorMachine\DataTransformer;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php b/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php
index 59154e3..180b8d3 100644
--- a/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php
+++ b/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\SupportVectorMachine;
+namespace Phpml\Tests\SupportVectorMachine;
 
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\SupportVectorMachine\Kernel;
diff --git a/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php b/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php
index f9d7c73..b9e40c0 100644
--- a/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php
+++ b/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Tokenization;
+namespace Phpml\Tests\Tokenization;
 
 use Phpml\Tokenization\WhitespaceTokenizer;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Phpml/Tokenization/WordTokenizerTest.php b/tests/Phpml/Tokenization/WordTokenizerTest.php
index 607c327..d18edb6 100644
--- a/tests/Phpml/Tokenization/WordTokenizerTest.php
+++ b/tests/Phpml/Tokenization/WordTokenizerTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace tests\Phpml\Tokenization;
+namespace Phpml\Tests\Tokenization;
 
 use Phpml\Tokenization\WordTokenizer;
 use PHPUnit\Framework\TestCase;