When we use a construct, such as (f(x) for x, y in C), we use multiple assignments in the for statement to unwrap a multi-valued tuple and then apply a function. The whole expression is a mapping. This is a common Python optimization to change the structure and apply a function.
We'll use our trip data from Chapter 4, Working with Collections. The following is a concrete example of unwrapping while mapping:
from typing import Callable, Iterable, Tuple, Iterator, AnyConv_F = Callable[[float], float]Leg = Tuple[Any, Any, float]def convert( conversion: Conv_F, trip: Iterable[Leg]) -> Iterator[float]: return ( conversion(distance) for start, end, distance in trip )
This higher-order function would be supported by ...
