Regex

Suppose we need to extract row and col from a string ‘R1C2_row62_col24.png’:

import re
some_string = 'R1C2_row62_col24.png'
m = re.match(r".*row(\d+)_col(\d+).*.png", some_string)
row = int(m.group(1))
col = int(m.group(2))
assert row == 62
assert col == 24

or suppose we want to extract a string from a name ‘some_class_name_123.jpg’:

import re
some_string = 'some_class_name_123.jpg'
m = re.match(r"(.+)_\d+.jpg", some_string)
assert m.group(1) == 'some_class_name'

Test here https://regex101.com/

Character	Action
.	any character
\d	only numbers (if we need decimal point user a backslash (.)
?	Zero or one character
+	One or many
*	Any character count

Good tutorial.