polars.Expr.list.diff

Expr.list.diff(n: int = 1, null_behavior: NullBehavior = 'ignore') → Expr

Calculate the n-th discrete difference of every sublist.

Parameters:

n

Number of slots to shift.

null_behavior{‘ignore’, ‘drop’}

How to handle null values.

Examples

>>> df = pl.DataFrame({"n": [[1, 2, 3, 4], [10, 2, 1]]})
>>> df.select(pl.col("n").list.diff())
shape: (2, 1)
┌────────────────┐
│ n              │
│ ---            │
│ list[i64]      │
╞════════════════╡
│ [null, 1, … 1] │
│ [null, -8, -1] │
└────────────────┘

>>> df.select(pl.col("n").list.diff(n=2))
shape: (2, 1)
┌───────────────────┐
│ n                 │
│ ---               │
│ list[i64]         │
╞═══════════════════╡
│ [null, null, … 2] │
│ [null, null, -9]  │
└───────────────────┘

>>> df.select(pl.col("n").list.diff(n=2, null_behavior="drop"))
shape: (2, 1)
┌───────────┐
│ n         │
│ ---       │
│ list[i64] │
╞═══════════╡
│ [2, 2]    │
│ [-9]      │
└───────────┘