Sorting files by Python naming convention

Sort by part of the naming convention

test.csv

001_0004_1.bmp
002_0004_1.bmp
003_0004_1.bmp
004_0003_1.bmp
005_0003_1.bmp
006_0003_1.bmp
007_0002_1.bmp
008_0002_1.bmp
009_0002_1.bmp
010_0001_1.bmp
011_0001_1.bmp
012_0001_1.bmp

Suppose you have a file name like the contents of test.csv above. The BMP file described in this CSV has the following naming convention (it is a properly created naming convention),

FFF_TTTT_C.bmp

--F: Frame number --T: Some kind of index --C: Index of the thing in the picture --The above numbers and indexes are separated by'_'

The contents of the above CSV file are sorted by frame number, For some reason

** "I want to sort by some index of T!" **

I'm assuming sorting when such a case comes out.

Way of thinking

1. Read the file name from CSV
2. Split the read file with'_'
3. Sort using some divided numbers
4. Shape the list and output to CSV

I created a program with the idea. If you search carefully, the function Ippatsu Dawn! I feel like I can do it with ...

Source code

##
# coding:utf-8
##

import csv
import pprint as pp

##
#Sort by naming convention
# inputlist:List to sort
# key_number:Specify which character string to sort by
# key_Returns an empty list if number exceeds the number of naming convention divisions
##
def Sort_by_Key(input_list,key_number,split='_'):
    #Split the file name and convert it to tuple format
    file_sort = []
    for t in input_list:
        sp_t = t.split(split)
        tap_sp_t = tuple(sp_t)
        file_sort.append(tap_sp_t)

    if len(file_sort[0]) < key_number:
        return []

    #sort
    file_sort.sort(key=lambda t: t[key_number])

    #Stick the splits together
    output_file = []
    for f in file_sort:
        s = split.join(f)
        output_file.append(s)

    return output_file

def main():
    #File reading
    op = open('test.csv','r')
    tpp = csv.reader(op)

    #Extract only the first row of csv
    test_file = []
    for t in tpp:
        test_file.append(t[0])

    op.close()

    #Original order
    print("before")
    pp.pprint(test_file)

    file_save = Sort_by_Key(test_file,1)

    print("\nafter")
    pp.pprint(file_save)

    #Conversion for storage
    row = len(file_save)
    col = 1
    SaveList = [file_save[col * i: col * (i + 1)] for i in range(row)]

    wp = open('output.csv','w')
    writer = csv.writer(wp, lineterminator='\n')
    writer.writerows(SaveList)
    wp.close()

if __name__=="__main__":
    main()

output.csv

010_0001_1.bmp
011_0001_1.bmp
012_0001_1.bmp
007_0002_1.bmp
008_0002_1.bmp
009_0002_1.bmp
004_0003_1.bmp
005_0003_1.bmp
006_0003_1.bmp
001_0004_1.bmp
002_0004_1.bmp
003_0004_1.bmp

Reference site

[1] Reading and writing CSV with Python [2] Introduction to Python-Lists, Tuples, Dictionaries [3] Python: Sorting objects [4] Concatenate / split character strings in Python: join (), split () [5] convert a flat list to list of list in python [6] Library: pprint