Question

I am facing a problem to match and replace certain words, not contained in http://

Present Regex:

 http://.*?\s+

This matches the pattern http://www.egg1.com http://www.egg2.com

I need a regex to match certain words contained outside the http://

Example:

"This is a sample. http://www.egg1.com and http://egg2.com. This regex will only match 
 this egg1 and egg2 and not the others contained inside http:// "

 Match: egg1 egg2

 Replaced: replaced1 replaced2

Final Output :

 "This is a sample. http://www.egg1.com and http://egg2.com. This regex will only 
  match this replaced1 and replaced2 and not the others contained inside http:// "

QUESTION:
Need to match certain patterns (as in example : egg1 egg2) unless they are part of http:// .Do not match egg1 and egg2 if they are present within http://

Answer 1

One solution I can think of is to form a combined pattern for HTTP-URLs and your pattern, then filter the matches accordingly:

import re

t = "http://www.egg1.com http://egg2.com egg3 egg4"

p = re.compile('(http://\S+)|(egg\d)')
for url, egg in p.findall(t):
  if egg:
    print egg

prints:

egg3
egg4

---

UPDATE: To use this idiom with re.sub(), just supply a filter function:

p = re.compile(r'(http://\S+)|(egg(\d+))')

def repl(match):
    if match.group(2):
        return 'spam{0}'.format(match.group(3))
    return match.group(0)

print p.sub(repl, t)

prints:

http://www.egg1.com http://egg2.com spam3 spam4