How to replace specific part of a substring (numbers) with dictionary values in python?

user_19108598 0
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I have a dictionary:

{1:"a"
 12:"b"
 3:"c"
 44:"dc"
 33:"dd"
 31: "ddf"}

String:

def12a 1fc 3 33 feg31

Output should replace these substrings from the dictionary:

defba afc c fefddf

I have tried few things using regex. I am able to replace, when the values are a separate word. But I am not able to do it when it is a substring.

What I tried: d-> dictionary s-> string

''.join(d[ch] if ch in d else ch for ch in s)

Thank you for the help

python replace string
2 Answers

You can use re.sub and after finding num use dict for replacing.

import re
dct = {1:"a", 12:"b", 3:"c", 44:"dc", 33:"dd", 31: "ddf"}
st = 'def12a 1fc 3 33 feg31'
res = re.sub(r'(\d+)', lambda x: dct[int(x.group())], st)
print(res)

defba afc c dd fegddf
user_17405770

This works for me:

def replace_numbers(s, replacements):
    # sort replacements by key
    # keys are descending
    # so '33' gets replaced before '3'
    sorted_replacements = sorted(replacements.items(), key=lambda x: x[0], reverse=True)
    # iterate over the sorted replacements
    for key, value in sorted_replacements:
        # replace the key with the value
        s = s.replace(str(key), value)
    return s

replacements = {
 1:"a",
 12:"b",
 3:"c",
 44:"dc",
 33:"dd",
 31: "ddf"
}

test_str = "def12a 1fc 3 33 feg31"

print(replace_numbers(test_str, replacements))

Output:

defba afc c dd fegddf
user_154005710
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