polars.Expr.list.count_match#

Expr.list.count_match(element: IntoExpr) → Expr[source]#

Count how often the value produced by element occurs.

Parameters:

element: An expression that produces a single value

Examples

>>> df = pl.DataFrame({"listcol": [[0], [1], [1, 2, 3, 2], [1, 2, 1], [4, 4]]})
>>> df.select(pl.col("listcol").list.count_match(2).alias("number_of_twos"))
shape: (5, 1)
┌────────────────┐
│ number_of_twos │
│ ---            │
│ u32            │
╞════════════════╡
│ 0              │
│ 0              │
│ 2              │
│ 1              │
│ 0              │
└────────────────┘