Switch operands in loops Python 3

Question

I want to be able to switch operands each time through a loop. So the first time through I'd like to add column. The second time through the loop I'd like to subtract from column. The third time through I would like to subtract from column and subtract from row. The fourth time through I'd like to subtract from column and add to row. Is this possible to write one loop to accomplish this instead of several? Thanks for the help!

#add            
for x in range(1,8): 
    if game[column+x][row] == 'W':
        game[column+x][row] = 'B'
    elif game[column+x][row] == 'B':
        return      
#subtract       
for x in range(1,8): 
    if game[column-x][row] == 'W':
        game[column-x][row] = 'B'
    elif game[column-x][row] == 'B':
        return
#etc....
for x in range(1,8): 
    if game[column-x][row-x] == 'W':
        game[column-x][row-x] = 'B'
    elif game[column-x][row-x] == 'B':
        return

for x in range(1,8): 
    if game[column-x][row+x] == 'W':
        game[column-x][row+x] = 'B'
    elif game[column-x][row+x] == 'B':
        return

What operand is changing? There seem to be inconsistencies in your code. Specifically, you are using `game[column+x]` the first time, but `game[column-x]` the other three times. — Peter, Feb 28 '17 at 20:46
You show three apparent operand changes here; please clarify the problem you're trying to solve. — Prune, Feb 28 '17 at 20:47
Also, are you trying to check the entire grid or and flip everything, or just the first `W`? — Mad Physicist, Feb 28 '17 at 21:13
BTW, add @MadPhyicist somewhere in your response so I get a notice. — Mad Physicist, Feb 28 '17 at 21:14
Possible duplicate? http://stackoverflow.com/questions/1620940/determining-neighbours-of-cell-two-dimensional-list — skrx, Feb 28 '17 at 21:15
Could you describe your goals in detail? And what exactly is the code supposed to? — skrx, Mar 01 '17 at 04:34

Marcos · Answer 1 · 2017-02-28T21:11:11.290

1

By your code I'm assuming you want to mark each 'W' surrounding cell with 'B'. This should be enough:

neighbours = [
  (-1, -1),
  (-1,  0),
  (-1,  1),
  ( 0, -1),
  ( 0,  0),
  ( 0,  1),
  ( 1, -1),
  ( 1,  0),
  ( 1,  1)
  ]

game = [
  ['W', 'W', 'E'],
  ['' ,  '',  ''],
  ['' ,  '',  '']
]

print game

row, col = 1, 1 # center of the game's table

for x, y in neighbours:
   if game[row + x][col + y] == 'W':
      game[row + x][col + y] = 'B'

print game

edited Feb 28 '17 at 21:11

answered Feb 28 '17 at 21:00

Marcos

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`for x, y in neighbors:` – Mad Physicist Feb 28 '17 at 21:09
@MadPhysicist indeed! Updated. – Marcos Feb 28 '17 at 21:11
@MadPhysicist I think that doesn't make a difference. The number of neighbours of any given position in the `game` table are always the same. – Marcos Feb 28 '17 at 21:14
Thanks for the help but this actually doesn't solve the problem. I actually want to be able to change the operands (+,-) so that I can go up to 8. I don't know if it possible. – code kid Feb 28 '17 at 21:45

score 0 · Accepted Answer · answered Mar 09 '17 at 20:29

0

I created a list of operands and iterated through the list.That worked

answered Mar 09 '17 at 20:29

code kid

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Switch operands in loops Python 3

2 Answers2