Check if values start with a binary substring

Source code

Description

Check if values start with a binary substring

Usage

<Expr>$bin$starts_with(sub)

Arguments

sub	Prefix substring.

Value

Expr returing a Boolean

Examples

library("polars")

colors = pl$DataFrame(
  name = c("black", "yellow", "blue"),
  code = as_polars_series(c("x00x00x00", "xffxffx00", "x00x00xff"))$cast(pl$Binary),
  prefix = as_polars_series(c("x00", "xffx00", "xffxff"))$cast(pl$Binary)
)

colors$select(
  "name",
  starts_with_lit = pl$col("code")$bin$starts_with("xff"),
  starts_with_expr = pl$col("code")$bin$starts_with(pl$col("prefix"))
)

#> shape: (3, 3)
#> ┌────────┬─────────────────┬──────────────────┐
#> │ name   ┆ starts_with_lit ┆ starts_with_expr │
#> │ ---    ┆ ---             ┆ ---              │
#> │ str    ┆ bool            ┆ bool             │
#> ╞════════╪═════════════════╪══════════════════╡
#> │ black  ┆ false           ┆ true             │
#> │ yellow ┆ true            ┆ false            │
#> │ blue   ┆ false           ┆ false            │
#> └────────┴─────────────────┴──────────────────┘