Removing lines with only digits - regex - regex

Question

I am new to both python and regex. I am trying to process a text file where I want to remove lines with only digits and space. This is the regular expression I am using.
^\s*[0-9]*\s*$
I am able to match the lines I want to remove (in notepad++ find dialog).
but when I try to do the same with python, the lines are not matched. Is there a problem in the regex itself or there is some problem with my python code?
Python code that I am using :
contacts = re.sub(r'^\s*[0-9]*\s*$','\n',contents)
Sample text
Age:30
Gender:Male
20
Name:संगीता शर्मा
HusbandsName:नरेश कुमार शर्मा
HouseNo:10/183
30 30
Gender:Female
21
Name:मोनू शर्मा
FathersName:कैलाश शर्मा
HouseNo:10/183
30
Gender:Male

Answer 1

Use re.sub in multiline mode:
contacts = re.sub(r'^\s*([0-9]+\s*)+$','\n',x, flags=re.M)
Demo
If you want the beginning ^ and ending $ anchors to kick in, then you want to be in multiline mode.
In addition, use the following to represent a line only containing clusters of numbers, possibly separated by whitespace:
^\s*([0-9]+\s*)+$

Answer 2

You don't even need regex for that, a simple str.translate() to remove characters you're not interested and check if something is left should more than suffice:
import string
clear_chars = string.digits + string.whitespace # a map of characters we'd like to check for
# open input.txt for reading, out.txt for writing
with open("input.txt", "rb") as f_in, open("output.txt", "wb") as f_out:
for line in f_in: # iterate over the input file line by line
if line.translate(None, clear_chars): # remove the chars, check if anything is left
f_out.write(line) # write the line to the output file
# uncomment the following if you want added newlines when pattern matched
# else:
# f_out.write("\n") # write a new line on match
Which will produce for your sample input:
Age:30
Gender:Male
Name:संगीता शर्मा
HusbandsName:नरेश कुमार शर्मा
HouseNo:10/183
Gender:Female
Name:मोनू शर्मा
FathersName:कैलाश शर्मा
HouseNo:10/183
Gender:Male
If you want the matching lines replaced with a new line, just uncomment the else clause.