Method: Polars::Functions#last

Defined in:

lib/polars/functions/lazy.rb

#last(*columns) ⇒ Expr

Get the last value.

Examples:

df = Polars::DataFrame.new(
  {
    "a" => [1, 8, 3],
    "b" => [4, 5, 2],
    "c" => ["foo", "bar", "baz"]
  }
)
df.select(Polars.last)
# =>
# shape: (3, 1)
# ┌─────┐
# │ c   │
# │ --- │
# │ str │
# ╞═════╡
# │ foo │
# │ bar │
# │ baz │
# └─────┘

df.select(Polars.last("a"))
# =>
# shape: (1, 1)
# ┌─────┐
# │ a   │
# │ --- │
# │ i64 │
# ╞═════╡
# │ 3   │
# └─────┘

df.select(Polars.last("b", "c"))
# =>
# shape: (1, 2)
# ┌─────┬─────┐
# │ b   ┆ c   │
# │ --- ┆ --- │
# │ i64 ┆ str │
# ╞═════╪═════╡
# │ 2   ┆ baz │
# └─────┴─────┘

Parameters:

• columns (Array) —

  One or more column names. If set to nil (default), returns an expression to take the last column of the context instead.

Returns:

• (Expr)

# File 'lib/polars/functions/lazy.rb', line 545

def last(*columns)
  if columns.empty?
    return cs.last.as_expr
  end

  col(*columns).last
end