nushell/crates/nu_plugin_polars
pyz4 90afb65329
feat(polars): expand polars shift to allow expressions inputs (#15834)
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# Description
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This PR seeks to expand the `polars shift` command to take expression
inputs. See third example below:

```nushell
Examples:
  Shifts the values by a given period
  > [1 2 2 3 3] | polars into-df | polars shift 2 | polars drop-nulls
  ╭───┬───╮
  │ # │ 0 │
  ├───┼───┤
  │ 0 │ 1 │
  │ 1 │ 2 │
  │ 2 │ 2 │
  ╰───┴───╯

  Shifts the values by a given period, fill absent values with 0
  > [1 2 2 3 3] | polars into-lazy | polars shift 2 --fill 0 | polars collect
  ╭───┬───╮
  │ # │ 0 │
  ├───┼───┤
  │ 0 │ 0 │
  │ 1 │ 0 │
  │ 2 │ 1 │
  │ 3 │ 2 │
  │ 4 │ 2 │
  ╰───┴───╯

  Shift values of a column, fill absent values with 0
  > [[a]; [1] [2] [2] [3] [3]]
                    | polars into-lazy
                    | polars with-column {b: (polars col a | polars shift 2 --fill 0)}
                    | polars collect
  ╭───┬───┬───╮
  │ # │ a │ b │
  ├───┼───┼───┤
  │ 0 │ 1 │ 0 │
  │ 1 │ 2 │ 0 │
  │ 2 │ 2 │ 1 │
  │ 3 │ 3 │ 2 │
  │ 4 │ 3 │ 2 │
  ╰───┴───┴───╯

```

# User-Facing Changes
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No breaking changes.

# Tests + Formatting
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An example test was added to `polars shift`

# After Submitting
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2025-05-28 08:10:49 -07:00
..