Sort clause for use in Frame’s square-bracket selector.

When a sort() object is present inside a DT[i, j, ...] expression, it will sort the rows of the resulting Frame according to the columns cols passed as the arguments to sort().

When used together with by(), the sort clause applies after the group-by, i.e. we sort elements within each group. Note, however, that because we use stable sorting, the operations of grouping and sorting are commutative: the result of applying groupby and then sort is the same as the result of sorting first and then doing groupby.

When used together with i (row filter), the i filter is applied after the sorting. For example:

DT[:10, :, sort(f.Highscore, reverse=True)]

will select the first 10 records from the frame DT ordered by the Highscore column.