polars.Expr.meta.is_length_preserving

Expr.meta.is_length_preserving() → bool

Whether or not this expression produces an output is length preserving.

By length preserving we mean the same length as it’s input.

Examples

>>> e = pl.col("foo").sum()
>>> e.meta.is_length_preserving()
False
>>> e = pl.col("foo").unique()
>>> e.meta.is_length_preserving()
False
>>> e = pl.col("foo") * pl.col("bar")
>>> e.meta.is_length_preserving()
True