polars.Expr.str.count_matches#

Expr.str.count_matches(pattern: str | Expr, *, literal: bool = False) → Expr[source]#

Count all successive non-overlapping regex matches.

Parameters:

pattern: A valid regular expression pattern, compatible with the regex crate.
literal: Treat pattern as a literal string, not as a regular expression.

Returns:

Expr: Expression of data type UInt32. Returns null if the original value is null.

Examples

>>> df = pl.DataFrame({"foo": ["123 bla 45 asd", "xyz 678 910t", "bar", None]})
>>> df.with_columns(
...     pl.col("foo").str.count_matches(r"\d").alias("count_digits"),
... )
shape: (4, 2)
┌────────────────┬──────────────┐
│ foo            ┆ count_digits │
│ ---            ┆ ---          │
│ str            ┆ u32          │
╞════════════════╪══════════════╡
│ 123 bla 45 asd ┆ 5            │
│ xyz 678 910t   ┆ 6            │
│ bar            ┆ 0            │
│ null           ┆ null         │
└────────────────┴──────────────┘

>>> df = pl.DataFrame({"bar": ["12 dbc 3xy", "cat\\w", "1zy3\\d\\d", None]})
>>> df.with_columns(
...     pl.col("bar")
...     .str.count_matches(r"\d", literal=True)
...     .alias("count_digits"),
... )
shape: (4, 2)
┌────────────┬──────────────┐
│ bar        ┆ count_digits │
│ ---        ┆ ---          │
│ str        ┆ u32          │
╞════════════╪══════════════╡
│ 12 dbc 3xy ┆ 0            │
│ cat\w      ┆ 0            │
│ 1zy3\d\d   ┆ 2            │
│ null       ┆ null         │
└────────────┴──────────────┘