TypeError：切片索引必须为整数或无，或具有__index__方法NLP

Question

I am running an example for NLP, using a stemmer function as a class method.

import nltk

class IndexedText(object):
    def __init__(self, stemmer, text):
        self._text = text 
        self._stemmer = stemmer
        self._index = nltk.Index((self._stem(word), i) for (i, word) in enumerate(text))
    def concordance(self, word, width=40):
        key = self._stem(word)
        wc = width/4 # words of context 
        print (self._index[key])
        for i in self._index[key]:
            lcontext = ' '.join(self._text[i-wc:i]) 
            rcontext = ' '.join(self._text[i:i+wc]) 
            ldisplay = '%*s' % (width, lcontext[-width:]) 
            rdisplay = '%-*s' % (width, rcontext[:width]) 
            print (ldisplay, rdisplay)
    def _stem(self, word):
        return self._stemmer.stem(word).lower()



 porter = nltk.PorterStemmer()

 grail = nltk.corpus.webtext.words('grail.txt')

 text = IndexedText(porter, grail)

Now i'm using concordance function on word 'lie' as follows :

text.concordance('lie')

And it gives me the error as below :

TypeError: slice indices must be integers or None or have an __index__ method

Where as the index['lie'] yields the output as all integers : [1824, 6451, 7038, 7080, 8450, 13860, 13965, 16684]

Answer 1

I noticed something in the line :

lcontext = ' '.join(self._text[i-wc:i])

the type of "i" here seems to be a tuple. you might have to modify it.