Functional Python Programming - Second Edition

Using the map() and reduce() functions to sanitize raw data

When doing data cleansing, we'll often introduce filters of various degrees of complexity to exclude invalid values. We may also include a mapping to sanitize values in the cases where a valid but improperly formatted value can be replaced with a valid but proper value.

We might produce the following output:

def comma_fix(data: str) -> float:    try:        return float(data)    except ValueError:        return float(data.replace(",", ""))def clean_sum(        cleaner: Callable[[str], float],        data: Iterable[str]    ) -> float:    return reduce(operator.add, map(cleaner, data))

We've defined a simple mapping, the comma_fix() class, that will convert data from a nearly correct string format into a usable floating-point ...