在for循环中读取csv文件时出现意外输出

Question

import csv
if __name__ == "__main__":
    words = ["great" , "thanks"]
    with open("data/sentiwordnet.tsv", "r") as f:
        reader = csv.DictReader(f,delimiter='\t')
        for word in xrange(len(words)):
             for row in reader:
                 if row['word_en'] == words[word]:
                    print float(row["positive"])
                    print float(row["negative"])
                    print row["synset"]

Results:

0.75
0.0 
124567

The results above are only for the 1st word, ie "great". The loop ends here - it doesn't go on to the next word.

Answer 1

Once you iterate through the rows in reader , it won't magically restart. Swap the for loops so that you iterate only once through reader :

for row in reader:
    for word in xrange(len(words)):

I'd just avoid iterating twice by just checking if each word is in a set of words you're interested in. It'll run faster:

import csv

if __name__ == "__main__":
    words = {"great" , "thanks"}  # sets are faster than lists for checking containment

    with open("data/sentiwordnet.tsv", "r") as f:
        reader = csv.DictReader(f, delimiter='\t')

        for row in reader:
            if row['word_en'] in words:
                print float(row["positive"])
                print float(row["negative"])
                print row["synset"]

You may also want to consider using a package like pandas for working with tables, it usually makes your life easier.