Python how to sum duplicates in list?

Question

I have this list

['OE21-k', 'OE28-k', 'OE21-k', 'OE-31-k', 'OE21-k', 'OE21-k', 'OE28-k']

And i want to know, how many OE21-k and how many OE28-k have. Is there any way to sum and calc how many duplicates are there?

Counter - https://docs.python.org/3/library/collections.html#collections.Counter — Joshua Nixon, Jul 02 '21 at 13:51
What do you mean by "sum" them? Do you mean simply counting the duplicates? — zr0gravity7, Jul 02 '21 at 13:52
https://stackoverflow.com/questions/2600191/how-can-i-count-the-occurrences-of-a-list-item — FloLie, Jul 02 '21 at 13:53

score 1 · Answer 1 · answered Jul 02 '21 at 13:52

1

Yes, the collections.Counter is easy to use:

from collections import Counter

items = ['OE21-k', 'OE28-k', 'OE21-k', 'OE-31-k', 'OE21-k', 'OE21-k', 'OE28-k']
c = Counter(items)
print(c)

Output:

Counter({'OE21-k': 4, 'OE28-k': 2, 'OE-31-k': 1})

answered Jul 02 '21 at 13:52

quamrana

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xaostheory · Accepted Answer · 2021-07-02T13:57:53.660

1

If you want to count the occurrences just use the count() method.

['OE21-k', 'OE28-k', 'OE21-k', 'OE-31-k', 'OE21-k', 'OE21-k', 'OE28-k'].count('OE21-k')

e.g.

occurences = {}
l = ['OE21-k', 'OE28-k', 'OE21-k', 'OE-31-k', 'OE21-k', 'OE21-k', 'OE28-k'] 
for item in l:
    if item not in occurences.keys():
        occurences[item] = l.count(item)

edited Jul 02 '21 at 13:57

answered Jul 02 '21 at 13:52

xaostheory

81
5

score 0 · Answer 3 · answered Jul 02 '21 at 13:52

0

occurences = {}

l = ['OE21-k', 'OE28-k', 'OE21-k', 'OE-31-k', 'OE21-k', 'OE21-k', 'OE28-k']

for item in l:
    if item in occurences:
        occurences[item] += 1
    else:
        occurences[item] = 1

answered Jul 02 '21 at 13:52

zr0gravity7

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Code-only answers are not particularly helpful. Please add some descriptions of how this code solves the problem. – Sven Eberth Jul 02 '21 at 22:21

Python how to sum duplicates in list?

3 Answers3