Regular expressions in a Python find-and-replace script? Update

Question

I'm new to Python scripting, so please forgive me in advance if the answer to this question seems inherently obvious.

I'm trying to put together a large-scale find-and-replace script using Python. I'm using code similar to the following:

infile = sys.argv[1]
charenc = sys.argv[2]
outFile=infile+'.output'

findreplace = [
('term1', 'term2'),
]

inF = open(infile,'rb')
s=unicode(inF.read(),charenc)
inF.close()

for couple in findreplace:
    outtext=s.replace(couple[0],couple[1])
    s=outtext

outF = open(outFile,'wb')
outF.write(outtext.encode('utf-8'))
outF.close()

How would I go about having the script do a find and replace for regular expressions?

Specifically, I want it to find some information (metadata) specified at the top of a text file. Eg:

Title: This is the title
Author: This is the author
Date: This is the date

and convert it into LaTeX format. Eg:

\title{This is the title}
\author{This is the author}
\date{This is the date}

Maybe I'm tackling this the wrong way. If there's a better way than regular expressions please let me know!

Thanks!

Update: Thanks for posting some example code in your answers! I can get it to work so long as I replace the findreplace action, but I can't get both to work. The problem now is I can't integrate it properly into the code I've got. How would I go about having the script do multiple actions on 'outtext' in the below snippet?

for couple in findreplace:
    outtext=s.replace(couple[0],couple[1])
    s=outtext

Thanks for the links. I've looked at re.sub() but haven't been able to work out how to plug it into my code. — 木川炎星
– 木川炎星, Commented Jun 14, 2010 at 11:20
your find-and-replace code has little to do with your actual task at hand. needed regex could not be reduces to a simple find-and-replace. — SilentGhost
– SilentGhost, Commented Jun 14, 2010 at 11:41

Amarghosh · Accepted Answer · 2010-06-14 11:40:58Z

5

>>> import re
>>> s = """Title: This is the title
... Author: This is the author
... Date: This is the date"""
>>> p = re.compile(r'^(\w+):\s*(.+)$', re.M)
>>> print p.sub(r'\\\1{\2}', s)
\Title{This is the title}
\Author{This is the author}
\Date{This is the date}

To change the case, use a function as replace parameter:

def repl_cb(m):
    return "\\%s{%s}" %(m.group(1).lower(), m.group(2))

p = re.compile(r'^(\w+):\s*(.+)$', re.M)
print p.sub(repl_cb, s)

\title{This is the title}
\author{This is the author}
\date{This is the date}

edited Jun 14, 2010 at 11:40

answered Jun 14, 2010 at 11:28

Amarghosh

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Sjoerd · Accepted Answer · 2010-06-14 11:14:39Z

1

See re.sub()

answered Jun 14, 2010 at 11:14

Sjoerd

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Tomalak · Accepted Answer · 2010-06-14 11:21:31Z

0

The regular expression you want would probably be along the lines of this one:

^([^:]+): (.*)

and the replacement expression would be

\\\1{\2}

answered Jun 14, 2010 at 11:21

Tomalak

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SilentGhost · Accepted Answer · 2010-06-14 11:23:07Z

0

>>> import re
>>> m = 'title', 'author', 'date'
>>> s = """Title: This is the title
Author: This is the author
Date: This is the date"""
>>> for i in m:
    s = re.compile(i+': (.*)', re.I).sub(r'\\' + i + r'{\1}', s)


>>> print(s)
\title{This is the title}
\author{This is the author}
\date{This is the date}

answered Jun 14, 2010 at 11:23

SilentGhost

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