public function testImputerWorksOnFitSamples()
{
$trainData = [[1, 3, 4], [6, 7, 8], [8, 7, 5]];
$data = [[1, 3, null], [6, null, 8], [null, 7, 5]];
$imputeData = [[1, 3, 5.66], [6, 5.66, 8], [5, 7, 5]];
$imputer = new Imputer(null, new MeanStrategy(), Imputer::AXIS_COLUMN, $trainData);
$imputer->transform($data);
$this->assertEquals($imputeData, $data, '', $delta = 0.01);
}