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Regular expression for substitution of similar pattern in a string in Python


I want to use a regular expression to detect and substitute some phrases. These phrases follow the same pattern but deviate at some points. All the phrases are in the same string.

For instance I have this string:

/this/is//an example of what I want /to///do

I want to catch all the words inside and including the // and substitute them with "".

To solve this, I used the following code:

import re
txt = "/this/is//an example of what i want /to///do"
re.search("/.*/",txt1, re.VERBOSE)
pattern1 = r"/.*?/\w+"
a = re.sub(pattern1,"",txt)

The result is:

' example of what i want '

which is what I want, that is, to substitute the phrases within // with "". But when I run the same pattern on the following sentence

"/this/is//an example of what i want to /do"

I get

' example of what i want to /do'

How can I use one regex and remove all the phrases and //, irrespective of the number of // in a phrase?


Solution

  • In your example code, you can omit this part re.search("/.*/",txt1, re.VERBOSE) as is executes the command, but you are not doing anything with the result.

    You can match 1 or more / followed by word chars:

    /+\w+
    

    Or a bit broader match, matching one or more / followed by all chars other than / or a whitspace chars:

    /+[^\s/]+
    
    • /+ Match 1+ occurrences of /
    • [^\s/]+ Match 1+ occurrences of any char except a whitespace char or /

    Regex demo

    import re
    
    strings = [
        "/this/is//an example of what I want /to///do",
        "/this/is//an example of what i want to /do"
    ]
    
    for txt in strings:    
        pattern1 = r"/+[^\s/]+"
        a = re.sub(pattern1, "", txt)
        print(a)
    

    Output

     example of what I want 
     example of what i want to