Method select

python/pathway/internals/table.py:389–428

Build a new table with columns specified by kwargs. Output columns' names are keys(kwargs). values(kwargs) can be raw values, boxed values, columns. Assigning to id reindexes the table. Args: args: Column references. kwargs: Column expressions with

(self, *args: expr.ColumnReference, **kwargs: Any)

    @arg_handler(handler=select_args_handler)
    @contextualized_operator
    def select(self, *args: expr.ColumnReference, **kwargs: Any) -> Table:
        """Build a new table with columns specified by kwargs.

        Output columns' names are keys(kwargs). values(kwargs) can be raw values, boxed
        values, columns. Assigning to id reindexes the table.


        Args:
            args: Column references.
            kwargs: Column expressions with their new assigned names.


        Returns:
            Table: Created table.


        Example:

        >>> import pathway as pw
        >>> t1 = pw.debug.table_from_markdown('''
        ... pet
        ... Dog
        ... Cat
        ... ''')
        >>> t2 = t1.select(animal=t1.pet, desc="fluffy")
        >>> pw.debug.compute_and_print(t2, include_id=False)
        animal | desc
        Cat    | fluffy
        Dog    | fluffy
        """
        new_columns = []

        all_args = combine_args_kwargs(args, kwargs)

        for new_name, expression in all_args.items():
            self._validate_expression(expression)
            column = self._eval(expression)
            new_columns.append((new_name, column))

        return self._with_same_universe(*new_columns)

    @trace_user_frame
    def __add__(self, other: Table) -> Table: