如何使用正则表达式或任何其他方法对字符串的特定模式进行子处理（python 2.7）？

Question

So the string url I have is 'http://helloworld.net/b/c/3?nw=174057&csid=fire.clan.com/gram/&din=&rand=52710&w=400&h=112' . This is in python 2.7.

Now the parameter rand in the url keeps changing and is always a 5 number length so it can be rand=12345 or 99999 and etc

Now I want to change that in this case ( 'rand=52710' ) to something like 'sub' or just ''

I have made attempts at this by using https://developers.google.com/edu/python/regular-expressions but didn't come up with a solid solution

Any help would be appreciated thanks.

Answer 1

Using Regex .

Ex:

import re
u = 'http://helloworld.net/b/c/3?nw=174057&csid=fire.clan.com/gram/&din=&rand=52710&w=400&h=112'
print re.sub("rand\=\d+", "SUB", u)

Output:

http://helloworld.net/b/c/3?nw=174057&csid=fire.clan.com/gram/&din=&SUB&w=400&h=112

Answer 2

Without regex, assuming that your claim " now the parameter rand in the url keeps changing and is always a 5 number length so it can be rand=12345 or 99999 " holds true:

url = "http://helloworld.net/b/c/3?csid=fire.clan.com/gram/&din=&rand=52710&w=400&h=112"
index = url.rfind("rand=")
if index != -1:
    url = url[:index] + url[index+11:]  # add 'sub' between url parts if you want it
# http://helloworld.net/b/c/3?csid=fire.clan.com/gram/&din=&w=400&h=112