How to filter elements in a list that occur only once
Question:
I need to filter and discard elements in a list that occur only once.
I have the following list of integers as input. I need to make a new list that contains only elements that do not have singular appearances.
item_list = [502, 502, 1341, 1342, 1500, 1500, 2521, 2521, 3078, 3688, 4191, 5185, 5701, 5701]
The desired output list would be like:
item_list = [502, 502, 1500, 1500, 2521, 2521, 5701, 5701]
Answers:
You can use collections.Counter:
from collections import Counter
item_list = [502, 502, 1341, 1342, 1500, 1500, 2521, 2521, 3078, 3688, 4191, 5185, 5701, 5701]
c = Counter(item_list)
out = [i for i in item_list if c[i] > 1]
print(out)
Prints:
[502, 502, 1500, 1500, 2521, 2521, 5701, 5701]
You can make a new list which checks every value that that doesn’t occur 1, then you set the list to the new list:
item_list = [502, 502, 1341, 1342, 1500, 1500, 2521, 2521, 3078, 3688, 4191,
5185, 5701, 5701]
new_list = [i for i in item_list if i != 1]
item_list = new_list
print(item_list)
I need to filter and discard elements in a list that occur only once.
I have the following list of integers as input. I need to make a new list that contains only elements that do not have singular appearances.
item_list = [502, 502, 1341, 1342, 1500, 1500, 2521, 2521, 3078, 3688, 4191, 5185, 5701, 5701]
The desired output list would be like:
item_list = [502, 502, 1500, 1500, 2521, 2521, 5701, 5701]
You can use collections.Counter:
from collections import Counter
item_list = [502, 502, 1341, 1342, 1500, 1500, 2521, 2521, 3078, 3688, 4191, 5185, 5701, 5701]
c = Counter(item_list)
out = [i for i in item_list if c[i] > 1]
print(out)
Prints:
[502, 502, 1500, 1500, 2521, 2521, 5701, 5701]
You can make a new list which checks every value that that doesn’t occur 1, then you set the list to the new list:
item_list = [502, 502, 1341, 1342, 1500, 1500, 2521, 2521, 3078, 3688, 4191,
5185, 5701, 5701]
new_list = [i for i in item_list if i != 1]
item_list = new_list
print(item_list)