daft.expressions.Expression.apply#

Expression.apply(func: Callable, return_dtype: Optional[daft.types.ExpressionType] = None, return_type: Optional[Any] = None) → daft.expressions.Expression[source]#

Apply a function on a given expression

Example

>>> def f(x_val: str) -> int:
>>>     return int(x_val) if x_val.isnumeric() else 0
>>>
>>> col("x").apply(f, return_dtype=int)
Parameters

  • func (Callable) – Function to run per value of the expression

  • return_dtype (Optional[Type], optional) – Return type of the function that was ran. This defaults to None which assumes the return type to be an arbitrary Python object.

Returns

New expression after having run the function on the expression

Return type

Expression