Python - how to replace the same char in a string with random integer for each occurence

Question

i have the following string for Example

str = "TESTXXXXX"

and i want to replace each X with a number, so the output should be something like this:

TEST98965

not :

TEST66666

i made the following python script to do the job.

from sys import argv
from random import randint

bincode = argv[1].lower()
replaced = bincode.replace('x',str(randint(0,9)))
print replaced

it takes a input from a user, and replaces each 'x' with a random number, the problem here is that the script replaces all the 'x' with the same number, i want each 'x' to be replaced with a different number, for example if user input is:

xxx

the output would be something like this:

986

Any suggestions on how to do that?

wap26 · Accepted Answer · 2017-12-05 13:49:54Z

3

You can use the re.sub function which supports a function as the replacement. https://docs.python.org/2/library/re.html#re.sub

The function will be called for each match for the regex pattern and must produce the replacement.

s = "TESTXXXXX"

import re
import random

def repl_fun(match):
    return str(random.randint(0,9))

replaced = re.sub('X', repl_fun, s)
print replaced

# output example:
# TEST57681

answered Dec 5, 2017 at 13:49

wap26

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3 Comments

Mohammad Athar Over a year ago

very nice; use a lambda function and it'll be even more concise! replaced = re.sub('X', lambda x: str(random.randint(0,9)), s)

KendoClaw Over a year ago

fantastic, but i have a question here, why did you set repl_fun() to take 1 argument and when calling it you didn't insert any arguments?

wap26 Over a year ago

@KendoClaw the replacement function is required to accept a single argument (the re.match object). In your case the replacement does not dependent on the matched text, so the argument is ignored.

Mohammad Athar · Accepted Answer · 2017-12-05 13:48:32Z

1

you have to generate a new random integer every time

from sys import argv
from random import randint

bincode = argv[1].lower()
bc = ''
tgchar= 'x'

for c in bincode:
    #print(c) not sure why I put this
    if c != tgchar:
        bc = bc + (c)
    else:
        bc = bc + (str(randint(0,9)))

print(bc)

edited Dec 5, 2017 at 13:48

answered Dec 5, 2017 at 13:40

Mohammad Athar

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2 Comments

KendoClaw Over a year ago

thank you for replying, this script prints each char in a new line, i don't want this, i want it all in the same string so i can save it to a file if i want.

Mohammad Athar Over a year ago

it prints some characters because of the (now commented out) print statement. at the end, it should print out the new string (the last line that says print(bc) )

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