How to edit lines of a text file based on regex conditions?-CodePudding

import re

re_for_identificate_1 = r""

with open("data_path/filename_1.txt","r ") as file:
    for line in file:
        #replace with a substring adding a space in the middle
        line = re.sub(re_for_identificate_1, " milesimo", line)

        #replace in txt with the fixed line

Example filename_1.txt :

unmilesimo primero
1001°

dosmilesimos quinto
2005°

tresmilesimos
3000°

nuevemilesimos doceavo
9012°

The correct output file that I need obtiene is this:

Rewrited input filename_1.txt

un milesimo primero
1001°

dos milesimos quinto
2005°

tres milesimos
3000°

nueve milesimos doceavo
9012°

What is the regex that I need and what is the best way to replace the fixed línes in their original positions in the input file?

CodePudding user response：

You can use file.seek(0) to go beginning of the file, then write data and truncate the file. Like this:

import re

re_for_identificate_1 = "(?<!^)milesimo"

tmp = ""
with open("data.txt", "r ") as file:
    for line in file:
        line = re.sub(re_for_identificate_1, " milesimo", line)
        tmp  = line
    file.seek(0)
    file.write(tmp)
    file.truncate()

The regex you want to use is "(?<!^)milesimo" to replace every instance of "milesimo" with " milesimo" but not at the beginning of a line.