use Cocur\Arff\Document;
use Cocur\Arff\Column\NumericColumn;
use Cocur\Arff\Column\NominalColumn;

$document = new Document('iris');
$document->addColumn(new NumericColumn('sepallength'));
$document->addColumn(new NumericColumn('sepalwidth'));
$document->addColumn(new NumericColumn('petallength'));
$document->addColumn(new NumericColumn('petalwidth'));
$document->addColumn(new NominalColumn('class', ['Iris-setosa','Iris-versicolor','Iris-virginica']));

$document->addData(['sepallength' => 5.1, 'sepalwidth' => 3.5, 'petallength' => 1.4, 'petalwidth' => 0.2, 'class' => 'Iris-setosa']);

$writer = new Writer();

$writer->render($document);           // returns rendered .arff file
$writer->write($document, 'iris.arff'); // writes .arff file to disk

use Cocur\Arff\Reader;

$reader = new Reader();
$document = $reader->readFile('irif.arff'); // returns Cocur\Arff\Document

$column = new DateColumn('created', 'yyyy-MM-dd HH:mm:ss');

use Cocur\Arff\Bridge\Plum\ArffWriter;

$writer = new ArffWriter('filename.arff', 'name', [
    new NumericColumn('sepallength'),
    new NumericColumn('sepalwidth'),
    new NumericColumn('petallength'),
    new NumericColumn('petalwidth'),
    new NominalColumn('class', ['Iris-setosa','Iris-versicolor','Iris-virginica']),
]);