Python finding index in a array

Question

I am trying to see if a company from a list of companies is in a line in a file. If it is I utilize the index of that company to increment a variable in another array. The following is my python code. I keep getting the following error: AttributeError: 'set' object has no attribute 'index'. I cannot figure out what is going wrong and think the error is the line that is surrounded by **.

companies={'white house black market', 'macy','nordstrom','filene','walmart'}
positives=[0 for x in xrange(len(companies))]
negatives=[0 for x in xrange(len(companies))]

for line in f:
    for company in companies:
        if company in line.lower():
            words=tokenize.word_tokenize(line)
            bag=bag_of_words(words)
            classif=classifier.classify(bag)
            if classif=='pos':
                **indice =companies.index(company)**
                positives[indice]+=1
            elif classif=='neg':
                **indice =companies.index(company)**
                negatives[indice]+=1

it should be companies=['white house black market', 'macy','nordstrom','filene','walmart'] — avasal
– avasal, Commented Nov 23, 2012 at 5:00

Aesthete · Accepted Answer · 2012-11-23 05:00:37Z

3

companies={'white house black market', 'macy','nordstrom','filene','walmart'}

Is a set. It has unique entries.

companies=['white house black market', 'macy','nordstrom','filene','walmart']

Is a list, and can multiple entries of the same value. It can also be indexed.

answered Nov 23, 2012 at 5:00

Aesthete

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Rohit Jain · Accepted Answer · 2012-11-23 05:11:57Z

2

companies={'white house black market', 'macy','nordstrom','filene','walmart'}

The above declaration is a set. And since a set has no ordering, you cannot get index of any elements from it.

>>> d = {2, 3, 4, 5}
>>> d
set([2, 3, 4, 5])  # It is a Set

So, to index an element, it should be declared as a List: -

companies=['white house black market', 'macy','nordstrom','filene','walmart']

edited Nov 23, 2012 at 5:11

answered Nov 23, 2012 at 5:01

Rohit Jain

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3 Comments

John Over a year ago

... don't {} represent dicts in python?

Rohit Jain Over a year ago

@johnthexiii.. Yeah they represent, but only when it is declared as key-value pair. Else it is a set. Try printing companies in interpreter. You will get that.

Rohit Jain Over a year ago

@johnthexiii.. I added example.

HYRY · Accepted Answer · 2012-11-23 05:00:05Z

1

companies is a set, and set has no order, so it can't use index(). You can change it to list:

companies=['white house black market', 'macy','nordstrom','filene','walmart']

answered Nov 23, 2012 at 5:00

HYRY

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