shift¶

Shifts values in the column by an offset.

Parameters:

n – The number of places to shift by. May be negative.
fill_value – The value to write to the empty spaces created by the shift. Defaults to null.

Examples

>>> t = pdt.Table(
...     {
...         "a": [5, -1, 435, -34, 8, None, 0],
...         "b": ["r", "True", "??", ".  .", "-1/12", "abc", "#"],
...     }
... )
>>> (
...     t
...     >> mutate(
...         x=t.a.shift(2, -40),
...         y=t.b.shift(1, arrange=t.a.nulls_last()),
...     )
...     >> show()
... )
Table <unnamed>, backend: PolarsImpl
shape: (7, 4)
┌──────┬───────┬─────┬───────┐
│ a    ┆ b     ┆ x   ┆ y     │
│ ---  ┆ ---   ┆ --- ┆ ---   │
│ i64  ┆ str   ┆ i64 ┆ str   │
╞══════╪═══════╪═════╪═══════╡
│ 5    ┆ r     ┆ -40 ┆ #     │
│ -1   ┆ True  ┆ -40 ┆ .  .  │
│ 435  ┆ ??    ┆ 5   ┆ -1/12 │
│ -34  ┆ .  .  ┆ -1  ┆ null  │
│ 8    ┆ -1/12 ┆ 435 ┆ r     │
│ null ┆ abc   ┆ -34 ┆ ??    │
│ 0    ┆ #     ┆ 8   ┆ True  │
└──────┴───────┴─────┴───────┘