Extracting words from txt file using python

问题

I want to extract all the words that are between single quotation marks from a text file. The text file looks like this:

u'MMA': 10,
=u'acrylic'= : 19,
== u'acting lessons': 2,
=u'aerobic': 141,
=u'alto': 2= 4,
=u&#= 39;art therapy': 4,
=u'ballet': 939,
=u'ballroom'= ;: 234,
= =u'banjo': 38,

And ideally, my output would look lie this:

MMA,
acrylic,
acting lessons,
...

From browsing posts, it seems like I should use some combination of NLTK / regex for python to accomplish this. I've tried the following:

import re

file = open('artsplus_categories.txt', 'r').readlines()

for line in file:
    list = re.search('^''$', file)

file.close()

And get the following error:

  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/re.py", line 142, in search
    return _compile(pattern, flags).search(string)
TypeError: expected string or buffer

I think the error might be caused by how I'm looking for the pattern. My logic is that I search for everything inside of the '....'.

What's tripping up re.py?

Thanks!

--------------------------------

Following Ashwini's comment:

import re

file = open('artsplus_categories.txt', 'r').readlines()

for line in file:
    list = re.search('^''$', line)

print list

#file.close()

But the output contains nothing:

Samuel-Finegolds-MacBook-Pro:~ samuelfinegold$ /var/folders/jv/9_sy0bn10mbdft1bk9t14qz40000gn/T/Cleanup\ At\ Startup/artsplus_categories_clean-393952531.278.py.command ; exit;
None
logout

@Rasco: here's the error I'm getting:

File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/re.py", line 177, in findall
    return _compile(pattern, flags).findall(string)
TypeError: expected string or buffer
logout

I'm using this code:

file2 = open('artsplus_categories.txt', 'r').readlines()
list = re.findall("'[^']*'", file2)
for x in list:
    print (x)

回答1:

Instead of passing the line to the regex you actually passed it the whole list(file). You should pass line to re.search not file.

for line in file:
    lis = re.search('^''$', line) # line not file

Don't use list, file as variable names. They are built-in functions.

Update:

with open('artsplus_categories.txt') as f:
    for line in f:
        print re.search(r"'(.*)'", line).group(1)
...         
MMA
acrylic
acting lessons
aerobic
alto
art therapy
ballet
ballroom
banjo

回答2:

Try this code example:

import re

file =  """u'MMA': 10,
        =u'acrylic'= : 19,
        == u'acting lessons': 2,
        =u'aerobic': 141,
        =u'alto': 2= 4,
        =u&#= 39;art therapy': 4,
        =u'ballet': 939,
        =u'ballroom'= ;: 234,
        = =u'banjo': 38,"""

list = re.findall("'[^']*'", file)
for x in list:
    print (x)

It shows the correct values. Keep in mind that one of the values in your example doesn't open the quote correctly, so the matches get broken there.

来源：https://stackoverflow.com/questions/17323801/extracting-words-from-txt-file-using-python

标签

python

regex

text

nltk