def partition(iterable, func):
    result = {}
    for i in iterable:
        result.setdefault(func(i), []).append(i) 
    return result

def group(seq):
    result = {}
    for item, category in seq:
        result.setdefault(category, []).append(item)
    return result 

# def is_odd(n):
#     return (n%2) == 1
# l = range(100)
# print partition(l, is_odd)
# print group( (item, is_odd(item)) for item in l)
# print group( (item, item%11) for item in l)    # no need to use lamda/def

def partition(iterable, func):
    result = {}
    for i in iterable:
        result.setdefault(func(i), []).append(i) 
    return result

def group(seq):
    result = {}
    for item, category in seq:
        result.setdefault(category, []).append(item)
    return result 

Partitioning a sequence into a dictionary keyed by function values

list, python, function

Python