I have a file that contains the following:

And I'm trying to write a cod that read every row and change the name to the following format:

keeping in mind that it should maintain letters (ABCD), add (_) after it and then add the numbers

if there is a zero such as ("ABCD**0**145"), it should remove it to be ("ABCD_145").

With single regex replacement:

df['Name'].str.replace(r'(\D)0?([1-9])', r'\1_\2')

• \D - non-digit character
• 0? - match optional 0 (if occurs)
• [1-9] - match any digit in range from 1 to 9

0     ABCD_145
1    ABCD_1445
2     ABCD_998