Question

How to remove elements of a list that are repeated less than k times in Python

Answer 1

from collections import Counter

def filter_by_frequency(lst, k):
    counts = Counter(lst)
    return [x for x in lst if counts[x] >= k]


lst = [1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 6, 7, 7, 7, 7, 8, 8, 8]
k = 3

print(filter_by_frequency(lst, k))


   
'''
run:
 
[3, 3, 3, 4, 4, 4, 4, 7, 7, 7, 7, 8, 8, 8]
   
'''

 

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Answer 2

from collections import Counter

def remove_in_place(lst, k):
    counts = Counter(lst)
    lst[:] = [x for x in lst if counts[x] >= k]



lst = [1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 6, 7, 7, 7, 7, 8, 8, 8]
k = 3

remove_in_place(lst, k)

print(lst)


   
'''
run:
 
[3, 3, 3, 4, 4, 4, 4, 7, 7, 7, 7, 8, 8, 8]
   
'''

 

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