polars.Expr.dt.days_in_month#

Expr.dt.days_in_month() → Expr[source]#

Extract the number of days in the month from the underlying Date representation.

Applies to Date and Datetime columns.

Returns the number of days in the month. The return value ranges from 28 to 31.

Returns:

Expr: Expression of data type Int8.

See also

month
is_leap_year

Examples

>>> from datetime import date
>>> df = pl.DataFrame(
...     {"date": [date(2001, 1, 1), date(2001, 2, 1), date(2000, 2, 1)]}
... )
>>> df.with_columns(pl.col("date").dt.days_in_month().alias("days_in_month"))
shape: (3, 2)
┌────────────┬───────────────┐
│ date       ┆ days_in_month │
│ ---        ┆ ---           │
│ date       ┆ i8            │
╞════════════╪═══════════════╡
│ 2001-01-01 ┆ 31            │
│ 2001-02-01 ┆ 28            │
│ 2000-02-01 ┆ 29            │
└────────────┴───────────────┘