Python text processing with regular expression

Question

I use python 2.7.5. I have got some files in the directory/sub directory. Sample of the file1 is given below

Title file name
    path1 /path/to/file
    options path2=/path/to/file1,/path/to/file2,/path/to/file3,/path/to/file4 some_vale1 some_vale2 some_value3=abcdefg some_value4=/path/to/value some_value5

I would like to insert the text /root/directory in the text file. Final outcome i would like to have is as followes:-

Title file name
    path1 /root/directory/path/tofile
    path2=/root/directory/path/to/file1,/root/directory/path/to/file2,/root/directory/path/to/file3,/root/directory/path/to/file4
    options some_vale1 some_vale2 some_value3=abcdefg some_value4=/path/to/value some_value5

The names path, options and path2 are same in all files. The files in the directory/subdirectory required to be modified with the same outcome as above. I tried to use the re.sub to find and replace the string. However I never got the output i wanted.

re.sub(r"([ \t =,])/", replace_text, text) where replace_text=/root/directory and text is the content of the file loaded with .read(). As of now i am just trying to figure out replacing/inserting. Getting path2 line in to next line is a different story. — sundar_ima
– sundar_ima, Commented Sep 29, 2013 at 11:43

Bohemian · Accepted Answer · 2013-09-29 21:43:50Z

1

This one-liner does the entire transformation:

str = re.sub(r'(options) (\S+)', r'\2\n    \1', str.replace('/path/', '/root/directory/path/')

See a live demo of this code

edited Sep 29, 2013 at 21:43

answered Sep 29, 2013 at 16:51

Bohemian♦

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Jerry · Accepted Answer · 2013-09-29 11:51:46Z

0

You can try this:

result = re.sub(r'([ \t =,])/', replace_text, text, 1)

The last 1 is to indicate the first match only, so that only the first path is substituted.

By the way, I think that you want to conserve the space/tab or comma right? Make replace_text like this:

replace_text = r'\1/root/directory/'

answered Sep 29, 2013 at 11:51

Jerry

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3 Comments

sundar_ima Over a year ago

That worked perfectely. However i had to remove ad i needed to replace all matching string. Can you tell me what does "\1" does in the r'\1/root/directory/' Now comes the second part. How do i get the path2 line to the next line?

Jerry Over a year ago

@sundar_ima Sorry, I didn't get notified of your comment :( The \1 matches the captured group, so that you're keeping the part you captured; otherwise, it'd end up as path1/root/directory/path/tofile. Also, that's all right, I thought that path2 was separate and would require a separate re.sub. Are the parts in the options separated by space? And is there always 4 paths and 5 values?

sundar_ima Over a year ago

Thanks for the clarification. Yes, option is always seperated by space and even path2=/path/to/file1 also seperated by space. There are some cases where path1, options and path2 are already in different lines.

sundar_ima · Accepted Answer · 2013-09-30 12:01:37Z

0

Ok. Got the answer from Bohemian and Jerry. Got it working with combined code.

str = re.sub(r'(options) (\S+)', r'\2\n    \1', re.sub(r'([ \t =,])/', replace_text, text))

edited Sep 30, 2013 at 12:01

answered Sep 30, 2013 at 1:15

sundar_ima

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