RuntimeError: dictionary changed size during iteration

[Shreeniket987]

So basically what I want is python code that counts how many times a word occurs in a paragraph for text auto summarization. I have managed to spit up the paragraph into sentences and sentences into words... So its a list of lists. And I am using the 'defaultdict" from the 'collections' library.
Here is my code:

from collections import defaultdict
freq = defaultdict(int)
for sentence in word_sent: #word_sent is my list of lists that I mentioned above.
    for word in sentence:
        freq[word] += 1               

I even tried like this:(Without using defaultdict)

freq = {}
for sentence in word_sent: #word_sent is my list of lists that I mentioned above.
    for word in sentence:
        if word not in freq.keys():
            freq[word] = 1
        else:
            freq[word] += 1

Yet I am getting the same error:

Error:
RuntimeError: dictionary changed size during iteration

And this is the only dictionary I have in my entire code.
Someone please help... Thank you!
P.S. This is my first post so please tell me if it is comprehensible or not.

[Yoriz]

I am not getting the error that you did, you didn't give a sample of word_sent so i made my own.

You should give a proper sample of word_sent so it can be tested in the same condition.

from collections import defaultdict

word_sent = [
    ["word", "word2", "word3", "word"],
    ["word5", "word1", "word1", "word"],
    ["word5", "word2", "word2", "word"],
]

freq = defaultdict(int)
for sentence in word_sent:  # word_sent is my list of lists that I mentioned above.
    for word in sentence:
        freq[word] += 1

print(freq)

Output:
defaultdict(<class 'int'>, {'word': 4, 'word2': 3, 'word3': 1, 'word5': 2, 'word1': 2})

[snippsat]

I also don't get error from your first code,can also use Counter from collection which as the name hint is made for counting stuff.
Has also useful method as most_common().
Test using word_sent that @Yoriz made.

>>> from collections import Counter
>>> 
>>> c = Counter(x for xs in word_sent for x in xs)
>>> c
Counter({'word': 4, 'word2': 3, 'word5': 2, 'word1': 2, 'word3': 1})
>>> c.most_common(2)
[('word', 4), ('word2', 3)]
>>> c.most_common(1)
[('word', 4)]

[buran]

it would be helpful to show the full traceback you get (in error tags)