Class UDFFunction

python/pathway/internals/udfs/__init__.py:240–295

Create a Python UDF (user-defined function) out of a callable. The output type of the UDF is determined based on its type annotation. Example: >>> import pathway as pw >>> import asyncio >>> table = pw.debug.table_from_markdown( ... ''' ... age | owner | pet ..

class UDFFunction(UDF):
    """Create a Python UDF (user-defined function) out of a callable.

    The output type of the UDF is determined based on its type annotation.

    Example:

    >>> import pathway as pw
    >>> import asyncio
    >>> table = pw.debug.table_from_markdown(
    ...     '''
    ... age | owner | pet
    ...  10 | Alice | dog
    ...   9 |   Bob | dog
    ...     | Alice | cat
    ...   7 |   Bob | dog
    ... '''
    ... )
    >>>
    >>> @pw.udf
    ... def concat(left: str, right: str) -> str:
    ...     return left + "-" + right
    ...
    >>> @pw.udf(propagate_none=True)
    ... def increment(age: int) -> int:
    ...     assert age is not None
    ...     return age + 1
    ...
    >>> res1 = table.select(
    ...     owner_with_pet=concat(table.owner, table.pet), new_age=increment(table.age)
    ... )
    >>> pw.debug.compute_and_print(res1, include_id=False)
    owner_with_pet | new_age
    Alice-cat      |
    Alice-dog      | 11
    Bob-dog        | 8
    Bob-dog        | 10
    >>>
    >>> @pw.udf
    ... async def sleeping_concat(left: str, right: str) -> str:
    ...     await asyncio.sleep(0.1)
    ...     return left + "-" + right
    ...
    >>> res2 = table.select(col=sleeping_concat(table.owner, table.pet))
    >>> pw.debug.compute_and_print(res2, include_id=False)
    col
    Alice-cat
    Alice-dog
    Bob-dog
    Bob-dog
    """

    def __init__(self, func: Callable, **kwargs):
        # this sets __wrapped__
        functools.update_wrapper(self, func)
        super().__init__(**kwargs)