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Check whether a value is in a vector

Source code

Description

Notice that to check whether a factor value is in a vector of strings, you need to use the string cache, either with pl$enable_string_cache() or with pl$with_string_cache(). See examples.

Usage

<Expr>$is_in(other)

Arguments

other numeric or string value; accepts expression input.

Value

Expr

Examples

library("polars")

pl$DataFrame(a = c(1:4, NA_integer_))$with_columns(
  in_1_3 = pl$col("a")$is_in(c(1, 3)),
  in_NA = pl$col("a")$is_in(pl$lit(NA_real_))
)

#> shape: (5, 3)
#> ┌──────┬────────┬───────┐
#> │ a    ┆ in_1_3 ┆ in_NA │
#> │ ---  ┆ ---    ┆ ---   │
#> │ i32  ┆ bool   ┆ bool  │
#> ╞══════╪════════╪═══════╡
#> │ 1    ┆ true   ┆ false │
#> │ 2    ┆ false  ┆ false │
#> │ 3    ┆ true   ┆ false │
#> │ 4    ┆ false  ┆ false │
#> │ null ┆ null   ┆ null  │
#> └──────┴────────┴───────┘

# this fails because we can't compare factors to strings
# pl$DataFrame(a = factor(letters[1:5]))$with_columns(
#   in_abc = pl$col("a")$is_in(c("a", "b", "c"))
# )

# need to use the string cache for this
pl$with_string_cache({
  pl$DataFrame(a = factor(letters[1:5]))$with_columns(
    in_abc = pl$col("a")$is_in(c("a", "b", "c"))
  )
})

#> shape: (5, 2)
#> ┌─────┬────────┐
#> │ a   ┆ in_abc │
#> │ --- ┆ ---    │
#> │ cat ┆ bool   │
#> ╞═════╪════════╡
#> │ a   ┆ true   │
#> │ b   ┆ true   │
#> │ c   ┆ true   │
#> │ d   ┆ false  │
#> │ e   ┆ false  │
#> └─────┴────────┘