Piwik\Plugins\CoreVisualizations\JqplotDataGenerator\Evolution::getSeriesData PHP Method

    private function getSeriesData($rowLabel, $columnName, DataTable\Map $dataTable)
    {
        $seriesData = array();
        foreach ($dataTable->getDataTables() as $childTable) {
            // get the row for this label (use the first if $rowLabel is false)
            if ($rowLabel === false) {
                $row = $childTable->getFirstRow();
            } else {
                $row = $childTable->getRowFromLabel($rowLabel);
            }
            // get series data point. defaults to 0 if no row or no column value.
            if ($row === false) {
                $seriesData[] = 0;
            } else {
                $seriesData[] = $row->getColumn($columnName) ?: 0;
            }
        }
        return $seriesData;
    }