Create a Date expression

Source code

Description

Create a Date expression

Usage

pl$date(year, month, day)

Arguments

year	An Expr or something coercible to an Expr, that must return an integer. Strings are parsed as column names. Floats are cast to integers.
month	An Expr or something coercible to an Expr, that must return an integer between 1 and 12. Strings are parsed as column names. Floats are cast to integers.
day	An Expr or something coercible to an Expr, that must return an integer between 1 and 31. Strings are parsed as column names. Floats are cast to integers.

Value

An Expr of type Date

See Also

• pl$datetime()
• pl$time()

Examples

library("polars")

df = pl$DataFrame(year = 2019:2021, month = 9:11, day = 10:12)

df$with_columns(
  date_from_cols = pl$date("year", "month", "day"),
  date_from_lit = pl$date(2020, 3, 5),
  date_from_mix = pl$date("year", 3, 5)
)

#> shape: (3, 6)
#> ┌──────┬───────┬─────┬────────────────┬───────────────┬───────────────┐
#> │ year ┆ month ┆ day ┆ date_from_cols ┆ date_from_lit ┆ date_from_mix │
#> │ ---  ┆ ---   ┆ --- ┆ ---            ┆ ---           ┆ ---           │
#> │ i32  ┆ i32   ┆ i32 ┆ date           ┆ date          ┆ date          │
#> ╞══════╪═══════╪═════╪════════════════╪═══════════════╪═══════════════╡
#> │ 2019 ┆ 9     ┆ 10  ┆ 2019-09-10     ┆ 2020-03-05    ┆ 2019-03-05    │
#> │ 2020 ┆ 10    ┆ 11  ┆ 2020-10-11     ┆ 2020-03-05    ┆ 2020-03-05    │
#> │ 2021 ┆ 11    ┆ 12  ┆ 2021-11-12     ┆ 2020-03-05    ┆ 2021-03-05    │
#> └──────┴───────┴─────┴────────────────┴───────────────┴───────────────┘

# floats are coerced to integers
df$with_columns(
  date_floats = pl$date(2018.8, 5.3, 1)
)

#> shape: (3, 4)
#> ┌──────┬───────┬─────┬─────────────┐
#> │ year ┆ month ┆ day ┆ date_floats │
#> │ ---  ┆ ---   ┆ --- ┆ ---         │
#> │ i32  ┆ i32   ┆ i32 ┆ date        │
#> ╞══════╪═══════╪═════╪═════════════╡
#> │ 2019 ┆ 9     ┆ 10  ┆ 2018-05-01  │
#> │ 2020 ┆ 10    ┆ 11  ┆ 2018-05-01  │
#> │ 2021 ┆ 11    ┆ 12  ┆ 2018-05-01  │
#> └──────┴───────┴─────┴─────────────┘

# if date can't be constructed, it returns null
df$with_columns(
  date_floats = pl$date(pl$lit("abc"), -2, 1)
)

#> shape: (3, 4)
#> ┌──────┬───────┬─────┬─────────────┐
#> │ year ┆ month ┆ day ┆ date_floats │
#> │ ---  ┆ ---   ┆ --- ┆ ---         │
#> │ i32  ┆ i32   ┆ i32 ┆ date        │
#> ╞══════╪═══════╪═════╪═════════════╡
#> │ 2019 ┆ 9     ┆ 10  ┆ null        │
#> │ 2020 ┆ 10    ┆ 11  ┆ null        │
#> │ 2021 ┆ 11    ┆ 12  ┆ null        │
#> └──────┴───────┴─────┴─────────────┘