polars.Expr.diff

Expr.diff(n: int = 1, null_behavior: str = 'ignore') → polars.internals.expr.Expr

Calculate the n-th discrete difference.

Parameters

n

number of slots to shift

null_behavior

{‘ignore’, ‘drop’}

Examples

>>> df = pl.DataFrame(
...     {
...         "a": [20, 10, 30],
...     }
... )
>>> df.select(pl.col("a").diff())
shape: (3, 1)
┌──────┐
│ a    │
│ ---  │
│ i64  │
╞══════╡
│ null │
├╌╌╌╌╌╌┤
│ -10  │
├╌╌╌╌╌╌┤
│ 20   │
└──────┘

polars.Expr.cumulative_eval polars.Expr.dot