Piwik\Plugins\CoreVisualizations\Visualizations\Sparkline::getValuesFromDataTableMap PHP Method

    protected function getValuesFromDataTableMap($dataTableMap, $columnToPlot)
    {
        $dataTableMap->applyQueuedFilters();
        $values = array();
        foreach ($dataTableMap->getDataTables() as $table) {
            if ($table->getRowsCount() > 1) {
                throw new Exception("Expecting only one row per DataTable");
            }
            $value = 0;
            $onlyRow = $table->getFirstRow();
            if (false !== $onlyRow) {
                if (!empty($columnToPlot)) {
                    $value = $onlyRow->getColumn($columnToPlot);
                } else {
                    $columns = $onlyRow->getColumns();
                    $value = current($columns);
                }
            }
            $values[] = $value;
        }
        return $values;
    }