dense_rank¶

The number of smaller or equal values in the column (not counting duplicates).

This function has two syntax alternatives, as shown in the example below. The pdt. version is a bit more flexible, because it allows sorting by multiple expressions.

Examples

>>> t = pdt.Table({"a": [5, -1, 435, -1, 8, None, 8]})
>>> (
...     t
...     >> mutate(
...         x=t.a.nulls_first().dense_rank(),
...         y=pdt.dense_rank(arrange=t.a.nulls_first()),
...     )
...     >> show()
... )
Table <unnamed>, backend: PolarsImpl
shape: (7, 3)
┌──────┬─────┬─────┐
│ a    ┆ x   ┆ y   │
│ ---  ┆ --- ┆ --- │
│ i64  ┆ i64 ┆ i64 │
╞══════╪═════╪═════╡
│ 5    ┆ 3   ┆ 3   │
│ -1   ┆ 2   ┆ 2   │
│ 435  ┆ 5   ┆ 5   │
│ -1   ┆ 2   ┆ 2   │
│ 8    ┆ 4   ┆ 4   │
│ null ┆ 1   ┆ 1   │
│ 8    ┆ 4   ┆ 4   │
└──────┴─────┴─────┘