Why does my loop write all data to a single column in my CSV file?

Question

I'm trying to make a loop that saves the progress in a game of Connect Four when a round ends. The csv has to display the game board as follows:

Each blank spot is represented by a 0, an 'O' is represented by a 2 and an 'X' by a 1.

This loop is supposed to loop through and change both the rows and the columns in the .csv file, but I get everything stacked in one column. Why is that?

if turn == 'X':
    turn = "O"
   
else:
    board_deepcopy = copy.deepcopy(my_board)
    ans = input('Type s to save your progress : ')
    if ans == 's':
     nop = input('Type in the name of your save file :')
     f = open(nop + '.csv', 'a', newline = '')
     writer = csv.writer(f)
     
     for y in range(board_col):
        list1 = []
        for l in range(board_col):
         if my_board[y][l] == 'X':
           board_deepcopy[y][l] = '1'
           list1.append(board_deepcopy[y][l])
           writer.writerow(list1[l])
           
         elif my_board[y][l] == 'O':
          
           
           board_deepcopy[y][l] = '2'
           list1.append(board_deepcopy[y][l])
           writer.writerow(list1[l])
          
         else:
          
           board_deepcopy[y][l] = '0'
           list1.append(board_deepcopy[y][l])
           writer.writerow(list1[l])
   
     f.close()
    
    turn = 'X'

A Windows Terminal example of display of board of 8 columns and 8 rows with an 'X' on column 1 and an 'O' on column 2:

      1    2    3    4    5    6    7    8
    ________________________________________
   A|' '  ' '  ' '  ' '  ' '  ' '  ' '  ' '|
   B|' '  ' '  ' '  ' '  ' '  ' '  ' '  ' '|
   C|' '  ' '  ' '  ' '  ' '  ' '  ' '  ' '|
   D|' '  ' '  ' '  ' '  ' '  ' '  ' '  ' '|
   E|' '  ' '  ' '  ' '  ' '  ' '  ' '  ' '|
   F|' '  ' '  ' '  ' '  ' '  ' '  ' '  ' '|
   G|' '  ' '  ' '  ' '  ' '  ' '  ' '  ' '|
   H| X    O   ' '  ' '  ' '  ' '  ' '  ' '|
    ---------------------------------------

.csv display:

  A  B  C  D  E  F  G  H 
1  0
2  0
3  0
4  0
5  0
6  0
7  0
8  1
... 
16 2 
17 0
18 0
19 0
... 
64 0

Answer 1

Your for loop is not doing what you want it to. You are appending to your list, but then you directly save the newly appended element to your .csv file. What you want to do is to save the entire list after your inner for loop is done to your file and then go on with the outer for loop. Here is how I think you want to design your loop:

import csv

board_col = 4
my_board = [['X', '0', '0', '0'], 
            ['0', 'X', '0', '0'], 
            ['0', '0', 'X', '0'], 
            ['0', '0', '0', 'X']]

f = open('try.csv', 'a', newline = '')
writer = csv.writer(f)

for y in range(board_col):
    list1 = []
    for l in range(board_col):
        if my_board[y][l] == 'X':
            list1.append('1')
        elif my_board[y][l] == 'O':
            list1.append('2')
        else:
            list1.append('0')
    writer.writerow(list1)

f.close()