pythonpython-polars

Default filter expression to "match anything"

What kind of polars expression (pl.Expr) might be used in a filter context that will match anything including nulls?

Use case: Type hinting and helper Functions that should return an polars.Expr.

Solution

  • The expression representing the literal value True might be used. See pl.lit for more details.

    Example.

    import polars as pl

df = pl.DataFrame({
    "a": [1, 2, None]
})

df.filter(pl.lit(True))

    shape: (3, 1)
┌──────┐
│ a    │
│ ---  │
│ i64  │
╞══════╡
│ 1    │
│ 2    │
│ null │
└──────┘

    Note. In general, simply True also works, but its not an instance of pl.Expr.