Select all array columns

Source code

Description

Usage

cs__array(inner = NULL, ..., width = NULL)

Arguments

inner	An optional inner selector to select columns having specific inner data types. If NULL, all inner types are selected.
…	These dots are for future extensions and must be empty.
width	An optional integer specifying the width of the array columns to select. If NULL, all widths are selected.

Value

A Polars selector

See Also

• cs for the documentation on operators supported by selectors.
• cs$by_dtype(): Select all columns matching the given dtype(s).
• cs$list(): Select all list columns.
• cs$nested(): Select all nested columns.

Examples

library("polars")

df <- pl$DataFrame(
  foo = list(c("xx", "yy"), c("x", "y")),
  bar = list(123, 456),
  baz = c(2.0, 5.5),
  .schema_overrides = list(
    foo = pl$Array(pl$String, 2),
    bar = pl$Array(pl$Int64, 1)
  )
)

# Select all array columns:
df$select(cs$array())

#> shape: (2, 2)
#> ┌───────────────┬───────────────┐
#> │ foo           ┆ bar           │
#> │ ---           ┆ ---           │
#> │ array[str, 2] ┆ array[i64, 1] │
#> ╞═══════════════╪═══════════════╡
#> │ ["xx", "yy"]  ┆ [123]         │
#> │ ["x", "y"]    ┆ [456]         │
#> └───────────────┴───────────────┘

# Select all columns except for those that are array:
df$select(!cs$array())

#> shape: (2, 1)
#> ┌─────┐
#> │ baz │
#> │ --- │
#> │ f64 │
#> ╞═════╡
#> │ 2.0 │
#> │ 5.5 │
#> └─────┘

# If you want to select specific array columns,
# you can specify the inner data type and/or width:
df$select(cs$array(cs$string()))

#> shape: (2, 1)
#> ┌───────────────┐
#> │ foo           │
#> │ ---           │
#> │ array[str, 2] │
#> ╞═══════════════╡
#> │ ["xx", "yy"]  │
#> │ ["x", "y"]    │
#> └───────────────┘

df$select(cs$array(width = 1))

#> shape: (2, 1)
#> ┌───────────────┐
#> │ bar           │
#> │ ---           │
#> │ array[i64, 1] │
#> ╞═══════════════╡
#> │ [123]         │
#> │ [456]         │
#> └───────────────┘

df$select(cs$array(cs$string() | cs$numeric(), width = 2))

#> shape: (2, 1)
#> ┌───────────────┐
#> │ foo           │
#> │ ---           │
#> │ array[str, 2] │
#> ╞═══════════════╡
#> │ ["xx", "yy"]  │
#> │ ["x", "y"]    │
#> └───────────────┘