Eran Moshe Eran Moshe - 1 year ago 110
Python Question

python - Yield improperly usage

Im pretty sure im using yield improperly:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import logging
from gensim import corpora, models, similarities
from collections import defaultdict
from pprint import pprint # pretty-printer
from six import iteritems
import openpyxl
import string
from operator import itemgetter

logging.basicConfig(format='%(asctime)s : %(levelname)s : %(message)s', level=logging.INFO)

#Creating a stoplist from file
with open('stop-word-list.txt') as f:
stoplist = [x.strip('\n') for x in f.readlines()]

corpusFileName = 'content_sample_en.xlsx'
corpusSheetName = 'content_sample_en'

class MyCorpus(object):
def __iter__(self):
wb = openpyxl.load_workbook(corpusFileName)
sheet = wb.get_sheet_by_name(corpusSheetName)
for i in range(1, (sheet.max_row+1)/2):
title = str(sheet.cell(row = i, column = 4).value.encode('utf-8'))
summary = str(sheet.cell(row = i, column = 5).value.encode('utf-8'))
content = str(sheet.cell(row = i, column = 10).value.encode('utf-8'))
yield reBuildDoc("{} {} {}".format(title, summary, content))

def removeUnwantedPunctuations(doc):
"change all (/, \, <, >) into ' ' "
newDoc = ""
for l in doc:
if l == "<" or l == ">" or l == "/" or l == "\\":
newDoc += " "
newDoc += l
return newDoc

def reBuildDoc(doc):
:param doc:
:return: document after being dissected to our needs.
doc = removeUnwantedPunctuations(doc).lower().translate(None, string.punctuation)
newDoc = [word for word in doc.split() if word not in stoplist]
return newDoc

corpus = MyCorpus()

tfidf = models.TfidfModel(corpus, normalize=True)

In the following example you can see me trying to create a corpus from an xlsx file. Im reading from the xlsx file 3 lines which are title summary and content and appending them into a big string. my
functions then adjust the text to my needs and in the end returns a big list of words. (for ex:
[hello, piano, computer, etc... ]
) in the end I yield the result but I get the following error:

Traceback (most recent call last):
File "C:/Users/Eran/PycharmProjects/tfidf/", line 101, in <module>
tfidf = models.TfidfModel(corpus, normalize=True)
File "C:\Anaconda2\lib\site-packages\gensim-0.13.1-py2.7-win-amd64.egg\gensim\models\", line 96, in __init__
File "C:\Anaconda2\lib\site-packages\gensim-0.13.1-py2.7-win-amd64.egg\gensim\models\", line 119, in initialize
for termid, _ in bow:
ValueError: too many values to unpack

I know the error is from the yield line because I had a different yield line that worked. It looked like this:

yield [word for word in dictionary.doc2bow("{} {} {}".format(title, summary, content).lower().translate(None, string.punctuation).split()) if word not in stoplist]

It was abit messy and hard to put functionallity to it so I've changed it as you can see in the first example.

Answer Source

the problem is not the yield per se, is what is yielded, the error said is from for termid, _ in bow this line said that you expect that bow contain a list of tuples or any other object containing exactly 2 element like (1,2),[1,2],"12",... but as it end giving to it the result of MyCorpus which is a string with obviously more than 2 element, hence the error, to fix this do either for termid in bow or in MyCorpus do yield reBuildDoc("{} {} {}".format(title, summary, content)), None so you yield a tuple of 2 object

to illustrate this check this example

>>> def fun(obj):
        for _ in range(2):
            yield obj

>>> for a,b in fun("xyz"):

Traceback (most recent call last):
  File "<pyshell#11>", line 1, in <module>
    for a,b in fun("xyz"):
ValueError: too many values to unpack (expected 2)
>>> for a,b in fun("xy"):

x y
x y
>>> for a,b in fun(("xy",None)):

xy None
xy None
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