Method intersect

python/pathway/internals/table.py:1025–1071

Restrict self universe to keys appearing in all of the tables. Args: tables: tables keys of which are used to restrict universe. Returns: Table: table with restricted universe, with the same set of columns Example: >>> import pathway as pw

(self, *tables: Table)

    @check_arg_types
    def intersect(self, *tables: Table) -> Table[TSchema]:
        """Restrict self universe to keys appearing in all of the tables.

        Args:
            tables: tables keys of which are used to restrict universe.

        Returns:
            Table: table with restricted universe, with the same set of columns


        Example:

        >>> import pathway as pw
        >>> t1 = pw.debug.table_from_markdown('''
        ...   | age  | owner  | pet
        ... 1 | 10   | Alice  | 1
        ... 2 | 9    | Bob    | 1
        ... 3 | 8    | Alice  | 2
        ... ''')
        >>> t2 = pw.debug.table_from_markdown('''
        ...   | cost
        ... 2 | 100
        ... 3 | 200
        ... 4 | 300
        ... ''')
        >>> t3 = t1.intersect(t2)
        >>> pw.debug.compute_and_print(t3, include_id=False)
        age | owner | pet
        8   | Alice | 2
        9   | Bob   | 1
        """
        if len(tables) == 0:
            warnings.warn("Empty argument list for Table.intersect().", stacklevel=5)
            return self
        all_args: list[Table] = [self, *tables]
        intersecting_universes = [tab._universe for tab in all_args]
        universe = self._get_universe_solver().get_intersection(*intersecting_universes)
        if universe.is_equal_to(self._universe):
            warnings.warn("Unnecessary call to Table.intersect().", stacklevel=5)
        for tab in tables:
            if universe.is_equal_to(tab._universe):
                warnings.warn(
                    "Table.intersect() can be replaced with Table.restrict() operation.",
                    stacklevel=5,
                )
                break
        return self._intersect(*tables)

    @contextualized_operator
    def _intersect(self, *tables: Table) -> Table[TSchema]: