Return the row indices that would sort the column(s)

Description

Usage

pl$arg_sort_by(
  ...,
  descending = FALSE,
  nulls_last = FALSE,
  multithreaded = TRUE,
  maintain_order = FALSE
)

Arguments

… \<dynamic-dots\> Column(s) to sort by. Can be character values indicating column names or Expr(s).

descending Sort in descending order. When sorting by multiple columns, this can be specified per column by passing a logical vector.

nulls_last Place null values last. When sorting by multiple columns, this can be specified per column by passing a logical vector.

multithreaded Sort using multiple threads.

maintain_order Whether the order should be maintained if elements are equal. If TRUE, streaming is not possible and performance might be worse since this requires a stable search.

Value

A polars expression

Examples

library("polars")

# Pass a single column name to compute the arg sort by that column.
df <- pl$DataFrame(
  a = c(0, 1, 1, 0),
  b = c(3, 2, 3, 2),
  c = c(1, 2, 3, 4)
)
df$select(pl$arg_sort_by("a"))

#> shape: (4, 1)
#> ┌─────┐
#> │ a   │
#> │ --- │
#> │ u32 │
#> ╞═════╡
#> │ 0   │
#> │ 3   │
#> │ 1   │
#> │ 2   │
#> └─────┘

# Compute the arg sort by multiple columns by either passing a list of
# columns, or by specifying each column as a positional argument.
df$select(pl$arg_sort_by("a", "b", descending = TRUE))

#> shape: (4, 1)
#> ┌─────┐
#> │ a   │
#> │ --- │
#> │ u32 │
#> ╞═════╡
#> │ 2   │
#> │ 1   │
#> │ 0   │
#> │ 3   │
#> └─────┘

# Use gather to apply the arg sort to other columns.
df$select(pl$col("c")$gather(pl$arg_sort_by("a")))

#> shape: (4, 1)
#> ┌─────┐
#> │ c   │
#> │ --- │
#> │ f64 │
#> ╞═════╡
#> │ 1.0 │
#> │ 4.0 │
#> │ 2.0 │
#> │ 3.0 │
#> └─────┘