"ValueError : list.remove(x): x not in list" 当 x 在列表中时

Question

I have tried many possible solutions but none of them worked. My code is a simple word counter that counts the frequency of words in song lyrics. Since short words should't be counted I wrote this code. My word and their count lists look like this.

 goodwords=["a", "my", "the", "I", "long", "up", "on"] 
 count=[26, 16, 16, 15, 12, 11, 11 ]

So I wrote this code to filter out short words.

for word in goodwords:
if len(word)<3:
        goodwords.index(word)
        count.remove(goodwords.index(word))
        goodwords.remove(word)

        

Python throws me this error:

ValueError: list.remove(x): x not in list

Even when I try to assign the index of the word to an int the same error is shown.

Answer 1

You should not modify a list while you are iterating through it. Your indices are changing when you remove something. Tr to simplify the task.

I would store word counts in a dictionary:

goodwords = ["a", "my", "the", "I", "long", "up", "on"]
count = [26, 16, 16, 15, 12, 11, 11 ]
wordcounts = dict(zip(goodwords, count))

To have only longer words, filter them:

wordcounts = {word: c for word, c in wordcounts.items()
              if len(word) > 3}

BTW, you can get the first part of the job done using the built-in collections.Counter :

>>> wordcounts = collections.Counter("one word and one more word".split())
>>> wordcounts
Counter({'one': 2, 'word': 2, 'and': 1, 'more': 1})

Answer 2

You can affect the loop if you modify a list you're looping in. Try creating a new list with the correct values instead.

for word in allwords:
if len(word)>3:
        goodwords.append(word)