Re: [Python-ideas] Allow a group by operation for dict comprehension

28 Jun 2018

      On Thu, Jun 28, 2018 at 10:24 AM Rob Cliffe via Python-ideas <
python-ideas@python.org> wrote:
...
def group_by(iterable, groupfunc, itemfunc=lambda x:x, sortfunc=lambda
x:x): # Python 2 & 3 compatible!
D = {}
    for x in iterable:
        group = groupfunc(x)
        D[group] = D.get(group, []) + [itemfunc(x)]
    if sortfunc is not None:
        for group in D:
            D[group] = sorted(D[group], key=sortfunc)
    return D
The fact that you didn't use ``setdefault`` here, opting for repeatedly
constructing new lists via concatenation, demonstrates the need for a
built-in or standard library tool that is easier to use.

I'll submit a proposal for your review soon.

Re: [Python-ideas] Allow a group by operation for dict comprehension

Michael Selik