Expr.filter

methodView source ↗

def filter(*predicates: td_IntoExprColumn | Iterable[td_IntoExprColumn]) -> Expr

Categories: filters

Apply a filter predicate to an expression.

Elements for which the predicate does not evaluate to true are discarded, evaluations to null are also discarded.

Useful in an aggregation expression.

Parameters

parameter

predicates

Expression(s) that evaluates to a boolean.

Examples

>>> import tabsdata as td
>>>
>>> tf: td.TableFrame ...
>>>
┌───────┬─────────┐
│ state ┆ tickets │
│ ---   ┆ ---     │
│ str   ┆ i64     │
╞═══════╪═════════╡
│ CA    ┆ 1       │
│ AL    ┆ 3       │
│ CA    ┆ 2       │
│ NY    ┆ 2       │
│ NY    ┆ 3       │
└───────┴─────────┘
>>>
>>> import tabsdata as td
>>> tf.group_by("state").agg(td.col("tickets")
>>>   .filter(td.col("tickets") !=2)
>>>   .sum().alias("sum_non_two"))
>>>
┌───────┬─────────────┐
│ state ┆ sum_non_two │
│ ---   ┆ ---         │
│ str   ┆ i64         │
╞═══════╪═════════════╡
│ AL    ┆ 3           │
│ NY    ┆ 3           │
│ CA    ┆ 1           │
└───────┴─────────────┘