PivotTable's and PivotMatrix's Map

PivotTable::create(array(
    ...
    'map' => array(
        'dataField' => function($dataField, $fieldInfo) {
            $v = $dataField;
            if ($v === 'dollar_sales - sum')
                $v = 'Sales (in USD)';
            else if ($v === 'dollar_sales - count')
                $v = 'Number of Sales';
            else if ($v === 'dollar_sales - avg')
                $v = 'Sales Average';
            return $v;
        },
    ),
    ...
));