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First solution in Clear category for Sort Array by Element Frequency by Sim0000
def frequency_sort(items):
# make digest
digest = []
use = set()
for item in items:
if item not in use:
use.add(item)
digest.append((item, items.count(item)))
# sort digest
digest.sort(key=lambda item: item[1], reverse=True)
# expand sorted digest to make result
result = []
for item, count in digest:
result += [item] * count
return result
if __name__ == '__main__':
print("Example:")
print(frequency_sort([4, 6, 2, 2, 6, 4, 4, 4]))
# These "asserts" are used for self-checking and not for an auto-testing
assert list(frequency_sort([4, 6, 2, 2, 6, 4, 4, 4])) == [4, 4, 4, 4, 6, 6, 2, 2]
assert list(frequency_sort(['bob', 'bob', 'carl', 'alex', 'bob'])) == ['bob', 'bob', 'bob', 'carl', 'alex']
assert list(frequency_sort([17, 99, 42])) == [17, 99, 42]
assert list(frequency_sort([])) == []
assert list(frequency_sort([1])) == [1]
print("Coding complete? Click 'Check' to earn cool rewards!")
Dec. 14, 2018
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