Method: Polars::Expr#sort_by

Defined in:

lib/polars/expr.rb

#sort_by(by, *more_by, reverse: false, nulls_last: false, multithreaded: true, maintain_order: false) ⇒ Expr

Sort this column by the ordering of another column, or multiple other columns.

In projection/ selection context the whole column is sorted. If used in a group by context, the groups are sorted.

Examples:

df = Polars::DataFrame.new(
  {
    "group" => [
      "one",
      "one",
      "one",
      "two",
      "two",
      "two"
    ],
    "value" => [1, 98, 2, 3, 99, 4]
  }
)
df.select(Polars.col("group").sort_by("value"))
# =>
# shape: (6, 1)
# ┌───────┐
# │ group │
# │ ---   │
# │ str   │
# ╞═══════╡
# │ one   │
# │ one   │
# │ two   │
# │ two   │
# │ one   │
# │ two   │
# └───────┘

Parameters:

• by (Object) —

  The column(s) used for sorting.

• reverse (Boolean) (defaults to: false) —

  false -> order from small to large. true -> order from large to small.

Returns:

• (Expr)

# File 'lib/polars/expr.rb', line 1587

def sort_by(by, *more_by, reverse: false, nulls_last: false, multithreaded: true, maintain_order: false)
  by = Utils.parse_into_list_of_expressions(by, *more_by)
  reverse = Utils.extend_bool(reverse, by.length, "reverse", "by")
  nulls_last = Utils.extend_bool(nulls_last, by.length, "nulls_last", "by")
  _from_rbexpr(
    _rbexpr.sort_by(
      by, reverse, nulls_last, multithreaded, maintain_order
    )
  )
end