Dyanmically Naming Files

[ovidius]

Hello Everybody

I wrote this code which takes 2 files removes any letters inside of them keeping only the phone numbers, then removes any duplicates and compares the files to find the common content.
The Code is this:

import re
import csv

filename_list=[]
file1 = input("Please input file1:   ")
filename_list.append(file1)
file2 = input("Please input file2:  ")
filename_list.append(file2)
duplicate_list=[]

def clean_file(filename):
	with open (filename,'r') as f:
		list1=f.readlines()
		for ch in list1:
			result=re.sub('[^0-9]','',ch)
			with open(('{}_clean.csv').format(filename),'a+') as cl:
				if len(result)<10:
					result=result.strip()
				else:
					cl.write(result + '\n')

def clean_duplicates(filename):
	lines_seen = set()
	with open(('{}_clean_dup.csv').format(filename),'w') as rf:
		duplicate_list.append(rf.name)
		for line in open(('{}_clean.csv').format(filename),'r'):
			if line not in lines_seen:
				rf.write(line)
				lines_seen.add(line)

def find_common():
	comp_file1 = open(duplicate_list[0], "r")
	comp_file2 = open(duplicate_list[1], "r")
	result = open("results.csv", "a")
	list1 = comp_file1.readlines()
	list2 = comp_file2.readlines()
	for i in list1:
		for j in list2:
			if i==j:
				result.write(i)

	comp_file1.close()
	comp_file2.close()
	result.close()

for filename in filename_list:
	clean_file(filename)
	clean_duplicates(filename)

find_common()

So the code works but I have a slight problem. The produced files get filenames like this: filename.csv_clean.csv and filename.csv_clean_dup.csv.

I tried .rsplit, .rpartition trying to drop the .csv extension from the initial filename but it doesn't work.

Can anyone help?