I need to find the frequency of elements in an unordered list
a = [1,1,1,1,2,2,2,2,3,3,4,5,5]
output->
b = [4,4,2,1,2]
Also I want to remove the duplicates from a
a = [1,2,3,4,5]
In Python 2.7 (or newer), you can use collections.Counter
:
import collections
a = [1,1,1,1,2,2,2,2,3,3,4,5,5]
counter=collections.Counter(a)
print(counter)
# Counter({1: 4, 2: 4, 3: 2, 5: 2, 4: 1})
print(counter.values())
# [4, 4, 2, 1, 2]
print(counter.keys())
# [1, 2, 3, 4, 5]
print(counter.most_common(3))
# [(1, 4), (2, 4), (3, 2)]
If you are using Python 2.6 or older, you can download it here.