Sort Expr by order of others

Description

Sort this column by the ordering of another column, or multiple other columns. If used in a groupby context, the groups are sorted.

Usage

<Expr>$sort_by(
  by,
  ...,
  descending = FALSE,
  nulls_last = FALSE,
  multithreaded = TRUE,
  maintain_order = FALSE
)

Arguments

`by`	One expression or a list of expressions and/or strings (interpreted as column names).
`…`	Ignored.
`descending`	A logical. If `TRUE`, sort in descending order.
`nulls_last`	A logical. If `TRUE`, place `null` values last insead of first.
`multithreaded`	A logical. If `TRUE`, sort using multiple threads.
`maintain_order`	A logical to indicate whether the order should be maintained if elements are equal.

Value

Expr

Examples

library("polars")

df = pl$DataFrame(
  group = c("a", "a", "a", "b", "b", "b"),
  value1 = c(98, 1, 3, 2, 99, 100),
  value2 = c("d", "f", "b", "e", "c", "a")
)

# by one column/expression
df$with_columns(
  sorted = pl$col("group")$sort_by("value1")
)

#> shape: (6, 4)
#> ┌───────┬────────┬────────┬────────┐
#> │ group ┆ value1 ┆ value2 ┆ sorted │
#> │ ---   ┆ ---    ┆ ---    ┆ ---    │
#> │ str   ┆ f64    ┆ str    ┆ str    │
#> ╞═══════╪════════╪════════╪════════╡
#> │ a     ┆ 98.0   ┆ d      ┆ a      │
#> │ a     ┆ 1.0    ┆ f      ┆ b      │
#> │ a     ┆ 3.0    ┆ b      ┆ a      │
#> │ b     ┆ 2.0    ┆ e      ┆ a      │
#> │ b     ┆ 99.0   ┆ c      ┆ b      │
#> │ b     ┆ 100.0  ┆ a      ┆ b      │
#> └───────┴────────┴────────┴────────┘

# by two columns/expressions
df$with_columns(
  sorted = pl$col("group")$sort_by(
    list("value2", pl$col("value1")),
    descending = c(TRUE, FALSE)
  )
)

#> shape: (6, 4)
#> ┌───────┬────────┬────────┬────────┐
#> │ group ┆ value1 ┆ value2 ┆ sorted │
#> │ ---   ┆ ---    ┆ ---    ┆ ---    │
#> │ str   ┆ f64    ┆ str    ┆ str    │
#> ╞═══════╪════════╪════════╪════════╡
#> │ a     ┆ 98.0   ┆ d      ┆ a      │
#> │ a     ┆ 1.0    ┆ f      ┆ b      │
#> │ a     ┆ 3.0    ┆ b      ┆ a      │
#> │ b     ┆ 2.0    ┆ e      ┆ b      │
#> │ b     ┆ 99.0   ┆ c      ┆ a      │
#> │ b     ┆ 100.0  ┆ a      ┆ b      │
#> └───────┴────────┴────────┴────────┘

# by some expression
df$with_columns(
  sorted = pl$col("group")$sort_by(pl$col("value1")$sort(descending = TRUE))
)

#> shape: (6, 4)
#> ┌───────┬────────┬────────┬────────┐
#> │ group ┆ value1 ┆ value2 ┆ sorted │
#> │ ---   ┆ ---    ┆ ---    ┆ ---    │
#> │ str   ┆ f64    ┆ str    ┆ str    │
#> ╞═══════╪════════╪════════╪════════╡
#> │ a     ┆ 98.0   ┆ d      ┆ b      │
#> │ a     ┆ 1.0    ┆ f      ┆ b      │
#> │ a     ┆ 3.0    ┆ b      ┆ b      │
#> │ b     ┆ 2.0    ┆ e      ┆ a      │
#> │ b     ┆ 99.0   ┆ c      ┆ a      │
#> │ b     ┆ 100.0  ┆ a      ┆ a      │
#> └───────┴────────┴────────┴────────┘