[FIXED] Convert String format to another format in Python

Issue

I extract a string a python file, the string is like this.

string = "'Interest Rate <b>%.2f</b> of <b>%.2f</b> can not change to <b>%s</b> of new loan product <b>%s</b>.'%(float(OldInterestRate),float(NewInterestRate),LoanProductOldDescription,LoanProductNewDescription)"

However, I want to use this to string to translate with Flask-Babel, the supported string with variable to support with Flask-Babel has to be as this:

string = "'Interest Rate <b>{OldInterestRate}</b> of <b>{NewInterestRate}</b> can not change to <b>{LoanProductOldDescription}</b> of new loan product <b>{LoanProductNewDescription}</b>.'.format(OldInterestRate=float(OldInterestRate),NewInterestRate=float(NewInterestRate),LoanProductOldDescription=LoanProductOldDescription,LoanProductNewDescription=LoanProductNewDescription)"

Because there are too files that has to change to this kind of string format that I could manually change the code one by one.

Therefore, I want to write a program that can convert that string into a format like above.

I have tried this

import re

def convert_format(variable):
    # Extract all matches of the format %(Value1,Value2,...)
    matches = re.findall(r"%\(([^)]+)\)", variable)
    
    # Splitting the matches to individual placeholders
    placeholders = [match.split(',') for match in matches]
    placeholders = [item for sublist in placeholders for item in sublist]  # Flatten the list
    
    # Replace the complex placeholder with the simple ones
    formatted_string = re.sub(r"%\(.+?\)", "%s", variable)
    
    # Replace the %s placeholders with the new format placeholders and prepare format() part
    format_part = []
    for placeholder in placeholders:
        formatted_string = formatted_string.replace("%s", "{" + placeholder + "}", 1)
        format_part.append(f"{placeholder}={placeholder}")

    # Add the format() part to the string
    formatted_string += ".format(" + ", ".join(format_part) + ")"
    if '%s' in formatted_string:
        formatted_string = formatted_string.replace('%s','')
    
    return formatted_string

variable = "'Interest Rate <b>%.2f</b> of <b>%.2f</b> can not change to <b>%s</b> of new loan product <b>%s</b>.'%(float(OldInterestRate),float(NewInterestRate),LoanProductOldDescription,LoanProductNewDescription)"
output_string = convert_format(variable)
print(output_string)

But the output result was not really correct as I wanted. Please kindly help, thanks.

Solution

Try:

import re


def get_variable_name(s):
    return re.sub(r"float\((.*?)\)", r"\g<1>", s)


string = "'Interest Rate <b>%.2f</b> of <b>%.2f</b> can not change to <b>%s</b> of new loan product <b>%s</b>.'%(float(OldInterestRate),float(NewInterestRate),LoanProductOldDescription,LoanProductNewDescription)"

part1, part2 = string.rsplit("%", maxsplit=1)
part2 = part2.strip(" )(")

variables = re.findall(r"((?:float\()?[^,]+\)?)", part2)
variable_names = [get_variable_name(v) for v in variables]

part1 = re.sub(r"%[^< ]+", lambda _, i=iter(variable_names): "{" + next(i) + "}", part1)
part2 = (
    ".format(" + ",".join(f"{n}={v}" for n, v in zip(variable_names, variables)) + ")"
)
print(part1 + part2)

Prints:

'Interest Rate <b>{OldInterestRate}</b> of <b>{NewInterestRate}</b> can not change to <b>{LoanProductOldDescription}</b> of new loan product <b>{LoanProductNewDescription}</b>.'.format(OldInterestRate=float(OldInterestRate),NewInterestRate=float(NewInterestRate),LoanProductOldDescription=LoanProductOldDescription,LoanProductNewDescription=LoanProductNewDescription)

Answered By - Andrej Kesely