Piwik\DataTable\Row::sumRowArray PHP Method

    protected function sumRowArray($thisColumnValue, $columnToSumValue)
    {
        if (is_numeric($columnToSumValue)) {
            if ($thisColumnValue === false) {
                $thisColumnValue = 0;
            }
            return $thisColumnValue + $columnToSumValue;
        }
        if ($columnToSumValue === false) {
            return $thisColumnValue;
        }
        if ($thisColumnValue === false) {
            return $columnToSumValue;
        }
        if (is_array($columnToSumValue)) {
            $newValue = $thisColumnValue;
            foreach ($columnToSumValue as $arrayIndex => $arrayValue) {
                if (!isset($newValue[$arrayIndex])) {
                    $newValue[$arrayIndex] = false;
                }
                $newValue[$arrayIndex] = $this->sumRowArray($newValue[$arrayIndex], $arrayValue);
            }
            return $newValue;
        }
        $this->warnWhenSummingTwoStrings($thisColumnValue, $columnToSumValue);
        return 0;
    }