feature request (function request)

[floer32]

I love where. What about another similar function, that takes predicates instead of values? Not sure what to call it, but it behaves like this:

def filterwhere(mappings, **preds):
    """ Like `where` but instead of value equality checks, use predicate functions.

    .. doctest ::

        >>> mappings = [{'foo': 'a', 'bar': 16},
        ...  {'foo': 'b', 'bar': 32},
        ...  {'foo': 'd', 'bar': 128, '': ''},
        ...  {'foo': 'e', 'bar': 123, 'baz': 'quux'},
        ...  {'foo': 'c', 'bar': 6400},
        ...  {'foo': 'f', 'bar': float("inf")},]
        >>> x = filterwhere(mappings, bar=lambda bar: bar < 100)
        >>> assert x == [{'foo': 'a', 'bar': 16}, {'foo': 'b', 'bar': 32}]
        >>> y = filterwhere(
        ...     mappings, bar=lambda n: n % 2 != 0 and n < 1000)
        >>> assert y == [{'foo': 'e', 'bar': 123, 'baz': 'quux'}]

    :param mappings: A sequence of mappings, for example a list of dicts.
    :param preds: Any number of predicate functions. Each mapping must
        pass `pred(mapping[key_of_mapping])` for each keyword argument pair of
        `key_of_mapping=pred`.
    :return: A sequence of mappings.
    """
    match = lambda m: all(pred(m[k]) for k, pred in preds.items())
    return filter(match, mappings)

[Suor]

I like such little neat things too. However, there is good solution for such situation in python - list comprehensions. So, even where is a stretch. I try to limit funcy scope at some level which makes me resistant to adding new things like this.

So I won't add it, sorry. I will still leave this issue open in case it will attract more interest. Then I'll probably reconsider.

[Suor]

P.S. You might want to look at this library for terser anonymous functions syntax.

[floer32]

Yeah, that's true. List comprehensions do solve this very well. Thanks for pointing out whatever, too!

[floer32]

closing