Expr.count

methodView source ↗

def count() -> Expr

Categories: aggregation

Aggregation operation that counts the non null values of the given column in the group.

Examples

>>> import tabsdata as td
>>>
>>> tf: td.TableFrame ...
>>>
┌──────┬──────┐
│ a    ┆ b    │
│ ---  ┆ ---  │
│ str  ┆ i64  │
╞══════╪══════╡
│ A    ┆ 1    │
│ B    ┆ 2    │
│ A    ┆ 3    │
│ B    ┆ 0    │
│ C    ┆ 5    │
│ null ┆ 6    │
│ C    ┆ null │
└──────┴──────┘
>>>
>>> tf.group_by(td.col("a")).agg(td.col("b")).count().alias("count"))
>>>
┌──────┬───────┐
│ a    ┆ count │
│ ---  ┆ ---   │
│ str  ┆ u32   │
╞══════╪═══════╡
│ null ┆ 1     │
│ A    ┆ 2     │
│ B    ┆ 2     │
│ C    ┆ 1     │
└──────┴───────┘