Method _join

python/pathway/stdlib/temporal/_window.py:147–254

(
        self,
        left: pw.Table,
        right: pw.Table,
        left_time_expression: pw.ColumnExpression,
        right_time_expression: pw.ColumnExpression,
        *on: pw.ColumnExpression,
        mode: pw.JoinMode,
        left_instance: pw.ColumnReference | None = None,
        right_instance: pw.ColumnReference | None = None,
    )

    @check_arg_types
    def _join(
        self,
        left: pw.Table,
        right: pw.Table,
        left_time_expression: pw.ColumnExpression,
        right_time_expression: pw.ColumnExpression,
        *on: pw.ColumnExpression,
        mode: pw.JoinMode,
        left_instance: pw.ColumnReference | None = None,
        right_instance: pw.ColumnReference | None = None,
    ) -> WindowJoinResult:
        def maybe_make_tuple(
            conditions: Sequence[pw.ColumnExpression],
        ) -> pw.ColumnExpression:
            if len(conditions) > 1:
                return pw.make_tuple(*conditions)
            elif len(conditions) == 1:
                return conditions[0]
            else:
                return None  # type: ignore

        check_joint_types(
            {
                "left_time_expression": (left_time_expression, TimeEventType),
                "right_time_expression": (right_time_expression, TimeEventType),
                "window.max_gap": (self.max_gap, IntervalType),
            }
        )

        if left_instance is not None and right_instance is not None:
            on = (*on, left_instance == right_instance)
        else:
            assert left_instance is None and right_instance is None

        left_on: list[pw.ColumnReference] = []
        right_on: list[pw.ColumnReference] = []
        for cond in on:
            cond_left, cond_right, _ = validate_join_condition(cond, left, right)
            left_on.append(cond_left)
            right_on.append(cond_right)

        concatenated_events = pw.Table.concat_reindex(
            left.select(
                key=left_time_expression,
                instance=maybe_make_tuple(left_on),
                is_left=True,
                original_id=left.id,
            ),
            right.select(
                key=right_time_expression,
                instance=maybe_make_tuple(right_on),
                is_left=False,
                original_id=right.id,
            ),
        )
        group_repr = self._compute_group_repr(
            concatenated_events, concatenated_events.key, concatenated_events.instance
        )