php-ml/docs/machine-learning/regression/svr.md
2018-03-20 17:25:25 +01:00

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# Support Vector Regression
Class implementing Epsilon-Support Vector Regression based on libsvm.
### Constructor Parameters
* $kernel (int) - kernel type to be used in the algorithm (default Kernel::RBF)
* $degree (int) - degree of the Kernel::POLYNOMIAL function (default 3)
* $epsilon (float) - epsilon in loss function of epsilon-SVR (default 0.1)
* $cost (float) - parameter C of C-SVC (default 1.0)
* $gamma (float) - kernel coefficient for Kernel::RBF, Kernel::POLYNOMIAL and Kernel::SIGMOID. If gamma is null then 1/features will be used instead.
* $coef0 (float) - independent term in kernel function. It is only significant in Kernel::POLYNOMIAL and Kernel::SIGMOID (default 0.0)
* $tolerance (float) - tolerance of termination criterion (default 0.001)
* $cacheSize (int) - cache memory size in MB (default 100)
* $shrinking (bool) - whether to use the shrinking heuristics (default true)
```
$regression = new SVR(Kernel::LINEAR);
$regression = new SVR(Kernel::LINEAR, $degree = 3, $epsilon=10.0);
```
### Train
To train a model simply provide train samples and targets values (as `array`). Example:
```
use Phpml\Regression\SVR;
use Phpml\SupportVectorMachine\Kernel;
$samples = [[60], [61], [62], [63], [65]];
$targets = [3.1, 3.6, 3.8, 4, 4.1];
$regression = new SVR(Kernel::LINEAR);
$regression->train($samples, $targets);
```
You can train the model using multiple data sets, predictions will be based on all the training data.
### Predict
To predict sample target value use `predict` method. You can provide one sample or array of samples:
```
$regression->predict([64])
// return 4.03
```