CODEWITHSUNDEEP
pythonregex
chrisg
chrisg

Reputation: 41705

Search for a String and replace it with a variable

I am trying to use regular expression to search a document fo a UUID number and replace the end of it with a new number. The code I have so far is:

read_file = open('test.txt', 'r+')
write_file = open('test.txt', 'w')

r = re.compile(r'(self.uid\s*=\s*5EFF837F-EFC2-4c32-A3D4\s*)(\S+)')
for l in read_file:
    m1 = r.match(l)
    if m1:
        new=(str,m1.group(2))
        new??????

This where I get stuck.

The file test.txt has the below UUID stored in it:

self.uid = '5EFF837F-EFC2-4c32-A3D4-D15C7F9E1F22'

I want to replace the part D15C7F9E1F22.

I have also tried this:

r = re.compile(r'(self.uid\s*=\s*)(\S+)')
for l in fp:
    m1 = r.match(l)
    new=map(int,m1.group(2).split("-")
    new[4]='RHUI5345JO'

But I cannot seem to match the string.

Thanks in advance for any help.

Upvotes: 2

Views: 460

Answers (2)

Lyndsey Ferguson
Lyndsey Ferguson

Reputation: 5384

I think your regular expression is off:

r = re.compile(r'(self.uid\s*=\s*5EFF837F-EFC2-4c32-A3D4\s*)(\S+)')

Should be:

r = re.compile(r"(self\.uid\s*=\s*'5EFF837F-EFC2-4c32-A3D4-)([^']*)'")

Then, when you have a match, grab group 1 and assign it to a variable and append your replacement string to it.

The ([^']*) group will search for any character up to the ' mark. That's your target remove group.

Edit: June 11th, 2010 @ 2:27 EST: Justin Peel has a good point. You can do a straight search and replace with this data. Unless you are looking for the pattern of 8 characters, followed by 4, 4, 4, and 12... In which case you could use the pattern:

r = re.compile(r"self\.uid\s*=\s*('\w{8}-(:?\w{4}-){3})(\w{12})'")

Upvotes: 1

Justin Peel
Justin Peel

Reputation: 47092

Why are you using a regex for such a straight forward substitution?

Couldn't you just use

for l in read_file:
    l.replace("5EFF837F-EFC2-4c32-A3D4-D15C7F9E1F22",
              "5EFF837F-EFC2-4c32-A3D4-RHUI5345JO")
    # Write to file..

or is there more to the story than you're telling us? Also, unless it is a too big of a file, I would recommend reading the whole file into a string and doing just one replace on it for the sake of speed.

Upvotes: 3

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