Regex with python dictionary-CodePudding

I am trying to do some "batch" find and replace.

I have the following string:

abc123 = abc122   V[2]   V[3]

I would like to find every instance of abc{someNumber} = and replace the instance's abc portion with int ijk{someNumber} =, and also replace V[3] with a keyword in a dictionary.

dictToReplace={"[1]": "_i", "[2]":"_j", "[3]":"_k"}

The expected end result would be:

ijk123 = ijk122   V_j   V_k

What is the best way to achieve this? RegEx for the first part? Can it also be used for the second?

CodePudding user response：

I'd split the logic in two steps:

1.) First replace the keyword abc\d 2.) Replace the keys found in dictionary with their respective values

import re

dictToReplace = {"[1]": "_i", "[2]": "_j", "[3]": "_k"}

s = "abc123 = abc122   V[2]   V[3]"

pat1 = re.compile(r"abc(\d )")
pat2 = re.compile("|".join(map(re.escape, dictToReplace)))

s = pat1.sub(r"ijk\1", s)
s = pat2.sub(lambda g: dictToReplace[g.group(0)], s)

print(s)

Prints:

ijk123 = ijk122   V_j   V_k

CodePudding user response：

Use a function as the replacement value in re.sub(). It can then look up the matched value in the dictionary to get the replacement.

string = 'abc123 = abc122   V[2]   V[3]'
# change abc### to ijk###
result = re.sub(r'abc(\d )', r'ijk\1', string)
# replace any V[###] with V_xxx from the dict.
result = re.sub(r'V(\[\d \])', lambda m: 'V'   dictToReplace.get(m.group(1), m.group(1)), result)