nushell/crates/nu_plugin_polars
pyz4 4e307480e4
polars: extend NuExpression::extract_exprs to handle records (#15553)
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# Description
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This PR seeks to simplify the syntax for commands that handle a list of
expressions (e.g., `select`, `with-column`, and `agg`) by enabling the
user to replace a list of expressions each aliased with `polars as` to a
single record where the key is the alias for the value. See below for
examples in several contexts.

```nushell
#  Select a column from a dataframe using a record
  > [[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select {c: ((polars col a) * 2)}
  ╭───┬────╮
  │ # │ c  │
  ├───┼────┤
  │ 0 │ 12 │
  │ 1 │  8 │
  │ 2 │  4 │
  ╰───┴────╯

#  Select a column from a dataframe using a mix of expressions and record of expressions
  > [[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select a b {c: ((polars col a) * 2)}
  ╭───┬───┬───┬────╮
  │ # │ a │ b │ c  │
  ├───┼───┼───┼────┤
  │ 0 │ 6 │ 2 │ 12 │
  │ 1 │ 4 │ 2 │  8 │
  │ 2 │ 2 │ 2 │  4 │
  ╰───┴───┴───┴────╯

#  Add series to the dataframe using a record
  > [[a b]; [1 2] [3 4]]
    | polars into-lazy
    | polars with-column {
        c: ((polars col a) * 2)
        d: ((polars col a) * 3)
      }
    | polars collect
  ╭───┬───┬───┬───┬───╮
  │ # │ a │ b │ c │ d │
  ├───┼───┼───┼───┼───┤
  │ 0 │ 1 │ 2 │ 2 │ 3 │
  │ 1 │ 3 │ 4 │ 6 │ 9 │
  ╰───┴───┴───┴───┴───╯

#  Group by and perform an aggregation using a record
  > [[a b]; [1 2] [1 4] [2 6] [2 4]]
                | polars into-lazy
                | polars group-by a
                | polars agg {
                    b_min: (polars col b | polars min)
                    b_max: (polars col b | polars max)
                    b_sum: (polars col b | polars sum)
                 }
                | polars collect
                | polars sort-by a
  ╭───┬───┬───────┬───────┬───────╮
  │ # │ a │ b_min │ b_max │ b_sum │
  ├───┼───┼───────┼───────┼───────┤
  │ 0 │ 1 │     2 │     4 │     6 │
  │ 1 │ 2 │     4 │     6 │    10 │
  ╰───┴───┴───────┴───────┴───────╯

```

# User-Facing Changes
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No breaking changes. Users now can use a mix of lists of expressions and
records of expressions where previously only lists of expressions were
accepted (e.g., in `select`, `with-column`, and `agg`).

# Tests + Formatting
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Example tests were added to `select`, `with-column`, and `agg`.

# After Submitting
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2025-04-14 16:56:52 -07:00
..
src polars: extend NuExpression::extract_exprs to handle records (#15553) 2025-04-14 16:56:52 -07:00
Cargo.toml build(deps): bump indexmap from 2.8.0 to 2.9.0 (#15531) 2025-04-09 13:15:29 +08:00
LICENSE Move dataframes support to a plugin (#12220) 2024-04-09 19:31:43 -05:00