Method: Polars::Expr#reverse

Defined in:
lib/polars/expr.rb

#reverse ⇒ Expr

Reverse the selection.

Examples:

df = Polars::DataFrame.new(
  {
    "A" => [1, 2, 3, 4, 5],
    "fruits" => ["banana", "banana", "apple", "apple", "banana"],
    "B" => [5, 4, 3, 2, 1],
    "cars" => ["beetle", "audi", "beetle", "beetle", "beetle"]
  }
)
df.select(
  [
    Polars.all,
    Polars.all.reverse.name.suffix("_reverse")
  ]
)
# =>
# shape: (5, 8)
# ┌─────┬────────┬─────┬────────┬───────────┬────────────────┬───────────┬──────────────┐
# │ A   ┆ fruits ┆ B   ┆ cars   ┆ A_reverse ┆ fruits_reverse ┆ B_reverse ┆ cars_reverse │
# │ --- ┆ ---    ┆ --- ┆ ---    ┆ ---       ┆ ---            ┆ ---       ┆ ---          │
# │ i64 ┆ str    ┆ i64 ┆ str    ┆ i64       ┆ str            ┆ i64       ┆ str          │
# ╞═════╪════════╪═════╪════════╪═══════════╪════════════════╪═══════════╪══════════════╡
# │ 1   ┆ banana ┆ 5   ┆ beetle ┆ 5         ┆ banana         ┆ 1         ┆ beetle       │
# │ 2   ┆ banana ┆ 4   ┆ audi   ┆ 4         ┆ apple          ┆ 2         ┆ beetle       │
# │ 3   ┆ apple  ┆ 3   ┆ beetle ┆ 3         ┆ apple          ┆ 3         ┆ beetle       │
# │ 4   ┆ apple  ┆ 2   ┆ beetle ┆ 2         ┆ banana         ┆ 4         ┆ audi         │
# │ 5   ┆ banana ┆ 1   ┆ beetle ┆ 1         ┆ banana         ┆ 5         ┆ beetle       │
# └─────┴────────┴─────┴────────┴───────────┴────────────────┴───────────┴──────────────┘

Returns:


1935
1936
1937
 
# File 'lib/polars/expr.rb', line 1935

def reverse
  _from_rbexpr(_rbexpr.reverse)
end