argSort style.multiKeyArgSort
fn
size_t[] multiKeyArgSort(Series[] keys, bool[] descending,
bool nullsLast = false)Sorts rows by several key columns at once: one stable pass per key, last key first, so earlier keys become the tie-break of later ones. Every pass applies the null placement. This is the column-input core; the frame adapter that resolves column names lives in ddn.df.frame.
Parameters
keys | the key columns, major first, of equal length |
descending | per-key direction flags (keys.length entries) |
nullsLast | nulls after valid entries in every key |
Returns
the permutation that sorts the rows,