2D Array out of range when it shouldn't be?? (PYTHON)

Question

I am running into an issue while I am iterating through my 2D array. I am going through my 4X3 grid and changing the requested coordinate from one character to another, rather "deleting" 'B' or 'W' and instead leaving nothing( the ' - ' character). I wont get into the niddy griddy of the code, but what I can say that I am currently working with this grid:

B W B W         <= trying =>       A1 A2 A3 A4
W B W B        to get these to     B1 B2 B3 B4
B W B W        <=correspond=>      C1 C2 C3 C4

B = black game pieces W = white game pieces

Here is a snip of code so you can see where I am going with it, then I will post what I want to happen.

removeB = input("~BLACK Player, remove one of your 'B's by typing in the coordinance: ")
print("")
removeW = input("~WHITE Player, remove one of your 'W's by typing in the coordinance: ")
print("")
newgrid = copy_grid(board)
for r in range(numrows):
    for c in range(numcols):
        if(removeB == 'A1'):
            newgrid[r][c] = '-'
        elif(removeB == 'A2'):
            newgrid[r][c+1] = '-'
        elif(removeB == 'A3'):
            newgrid[r][c+2] = '-'
        elif(removeB == 'A4'):
            newgrid[r][c+3] = '-'
        elif(removeB == 'B1'):
            newgrid[r+1][c] = '-'
   etc....etc...etc...'
        if(removeW == 'A1'):
            newgrid[r-1][c-1] = '-'
        elif(removeW == 'A2'):
            newgrid[r-1][c-1] = '-'
        elif(removeW == 'A3'):
            newgrid[r-1][c+1] = '-'
        elif(removeW == 'A4'):
            newgrid[r-1][c+2] = '-'
        elif(removeW == 'B1'):
            newgrid[r][c-1] = '-'
     etc....etc...etc...

You will see that once I go into the 2nd if statement that I i change the formatting of the newgrid coordinate checking as far as index values. I did this for testing purposes as I now know that I receive the same error message for both methods. Hence my confusion.... Also, I know that I will run into an issue because inside both if/else statements, I am checking a location even if it is not that player's Color. I will get to this once I get the coordinates to cooperate.

Here is the output that I want when removeB= A1 and removeW = C4 :

  - W B W   
  W B W B
  B W B -

Here is the error message :

Traceback (most recent call last):
  File "<pyshell#29>", line 1, in <module>
  initial()
  File "C:\Users\Ted\Desktop\Lab3.1Final.py", line 84, in initial
  newgrid[r][c] = '-'
  IndexError: list index out of range

Line 84 is the line right after the very first if(removeB == 'A1') executes and it goes to change the value at the desired coordinates.

Please let me know if I should submit any other code pertaining to this question if it would help in providing the best answers. Thanks in advance!

Not directly related to your problem, but you should look at the switch/case statement (at least, Python's version) as shown here: http://stackoverflow.com/questions/11479816/what-is-the-python-equivalent-for-a-case-switch-statement — Steve Byrne, Nov 03 '16 at 07:52
Maybe I am missing something, but lets say they type in A4, the if statement doesn't seem to break so it will look through the first time and work, then it will look 3 more times, breaking each time because c (1,2,3,4) will first be 0 + 4 = 4 (good answer!) then the next look 1+4 = 5 (bad answer) and so on... Why is it in a loop at all here? I think it would be best to approach this in a whole new way (I can help farther in chat) — Steve Byrne, Nov 03 '16 at 07:59

score 1 · Accepted Answer · answered Nov 03 '16 at 08:08

You can go about this much more simply:

In [1]: grid = [['B','W','B','W'],['W','B','W','B'],['B','W','B','W']]

In [2]: def show_grid(grid):
    ...:     print(*(" ".join(row) for row in grid),sep='\n')
    ...:     

In [3]: def delete_at_coordinate(grid,coordinate):
    ...:     row = ord(coordinate[0]) - 65
    ...:     col = int(coordinate[1]) - 1
    ...:     grid[row][col] = '-'
    ...:     

In [4]: removeB = 'A1'

In [5]: removeA = 'C4'

In [6]: show_grid(grid)
B W B W
W B W B
B W B W

In [7]: delete_at_coordinate(grid,removeB)

In [8]: delete_at_coordinate(grid,removeA)

In [9]: show_grid(grid)
- W B W
W B W B
B W B -

2D Array out of range when it shouldn't be?? (PYTHON)

1 Answers1