Table.Group(table as table, key as any, aggregatedColumns as list, optional groupKind as nullable number, optional comparer as nullable function) as table


Groups the rows of table by the key columns defined by key. The key can either be a single column name, or a list of column names. For each group, a record is constructed containing the key columns (and their values), along with any aggregated columns specified by aggregatedColumns. Optionally, groupKind and comparer may also be specified.

If the data is already sorted by the key columns, then a groupKind of GroupKind.Local can be provided. This may improve the performance of grouping in certain cases, since all the rows with a given set of key values are assumed to be contiguous.

When passing a comparer, note that if it treats differing keys as equal, a row may be placed in a group whose keys differ from its own.

This function does not guarantee the ordering of the rows it returns.

Example 1

Group the table adding an aggregate column [total] which contains the sum of prices ("each List.Sum([price])").


        [CustomerID = 1, price = 20],
        [CustomerID = 2, price = 10],
        [CustomerID = 2, price = 20],
        [CustomerID = 1, price = 10],
        [CustomerID = 3, price = 20],
        [CustomerID = 3, price = 5]
    {"total", each List.Sum([price])}


        [CustomerID = 1, total = 30],
        [CustomerID = 2, total = 30],
        [CustomerID = 3, total = 25]
    {"CustomerID", "total"}