CODEWITHSUNDEEP
pythoncounter
user3470490
user3470490

Reputation: 3

sum of counter object of a list within a list

I am trying to find the sum of occurrence of a words from a list in a multiple lists. the list objects within list is huge so I used just a dummy instance

multiple=[['apple','ball','cat']['apple','ball']['apple','cat'].......]
words=['apple','ball','cat','duck'......]
word = 'apple' 
cnt = Counter()
total = 0
for i in multiple:
        for j in i:
            if word in j:
                cnt[word] +=1
                total += cnt[word]

I wanted an output like this:

{'apple':3,'ball':2,'cat':2}

Upvotes: 0

Views: 231

Answers (2)

roippi
roippi

Reputation: 25954

You can just feed the Counter a generator expression:

cnt = Counter(word for sublist in multiple for word in sublist)

cnt
Out[40]: Counter({'apple': 3, 'ball': 2, 'cat': 2})

sum(cnt.values())
Out[41]: 7

I didn't really see the point of your words list. You didn't use it.

If you need to filter out words that are not in words, make words a set, not a list.

words = {'apple','ball','cat','duck'}

cnt = Counter(word for sublist in multiple for word in sublist if word in words)

Otherwise you get O(n**2) behavior in what should be a O(n) operation.

Upvotes: 2

pts
pts

Reputation: 87281

This works in Python 2.7 and Python 3.x:

from collections import Counter

multiple=[['apple','ball','cat'],['apple','ball'],['apple','cat']]
words=['apple','ball','cat','duck']
cnt = Counter()
total = 0
for i in multiple:
        for word in i:
            if word in words:
                cnt[word] +=1
                total += 1
print cnt  #: Counter({'apple': 3, 'ball': 2, 'cat': 2})
print dict(cnt)  #: {'apple': 3, 'ball': 2, 'cat': 2}
print total  #: 7
print sum(cnt.values())  #: 7

In Python 2.x you should use .itervalues() instead of .values() even though both work.

A bit shorter solution, based on roippi's answer:

from collections import Counter
multiple=[['apple','ball','cat'],['apple','ball'],['apple','cat']]
cnt = Counter(word for sublist in multiple for word in sublist)
print cnt  #: Counter({'apple': 3, 'ball': 2, 'cat': 2})

Upvotes: 0

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