Replacing 'match' object with string, Python

Question

I want to replace certain lines in my text with another string. So far I was able to locate the text I want to replace with:

text = open('sample','r').read()
regex = re.compile('.*#= min, max\s')
for match in regex.finditer(text):
    print match.group(0) #this is what i want to replace

EDIT: also tried

text = open('sample','r').read().split('\n')
for line in text:
    line = re.sub('.*#= min, max\s', "HOLA", line)

The text stays the same. Could it be that my regex is messed up? I used the same one somewhere else and there was no problem. Also its a simple regex.

How do I switch it to another line? Thanks!

I guess you're looking for re.sub. docs.python.org/library/re.html#re.sub — Gandi
– Gandi, Commented Sep 12, 2012 at 8:31
To your edit: Of course the text stays the same. You iterate it over and modify the variable line, but drop its contents immediately. Try newtext=[re.sub('.*#= min, max\s', "HOLA", line) for line in text]. — glglgl
– glglgl, Commented Sep 12, 2012 at 8:38

Inbar Rose · Accepted Answer · 2012-09-12 09:31:09Z

1

try:

subbedlines = []

with open('sample','r') as textreader:
    lines = textreader.read().split('\n')

for line in lines:
    subbedlines.append(re.sub('.*#= min, max\s', "HOLA", line))

should work if your regex is correct and your lines in the text file are matching. to write the file again simply do:

with open('sample','w') as textwriter:
    for line in subbedlines:
        textwriter.write("%s\n" % line)

answered Sep 12, 2012 at 9:31

Inbar Rose

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glglgl · Accepted Answer · 2012-09-12 08:34:06Z

1

I am not sure if I understand what you want. But the regex objects's sub() function can be called with either the text you want to replace with, such as

regex.sub("new text", text)

or with a function taking a match object and returning the text to be replaced with, such as

def reverse(match):
    return match.group(0)[-1::-1]
    # or do whatever else you might want to do
regex.sub(reverse, text)

so that you are completely free to decide what to replace with.

Be aware that due to the greedy .* in your regex, this might replace only the last part. Be sure to work with $ (end of line), ^ (start of line), .*? (non-greedy version) and perhaps the re option MULTILINE.

answered Sep 12, 2012 at 8:34

glglgl

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1 Comment

Yotam Over a year ago

As you can see I tried it (just edited my question), but it doesn't work and I don't know why\

Meph · Accepted Answer · 2012-09-12 11:20:39Z

0

Maybe i dont understand, but why are you iterating line after line, instead of just replacing every it like this:

import re

with open("text.txt") as text:
    new_text = re.sub("jj", "xx", text.read())
    with open("newtext.txt", "w") as result:
        result.write(new_text)

but maybe I am missing something.

answered Sep 12, 2012 at 11:20

Meph

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