List index out of range (Python 2.7) - python-2.7

Question

I feel like I am constantly having this problem when I am writing a program, what I want to do is iterate over every value in my nested list and say that if it's not a zero, make it one.
Here is the error I am getting:
Traceback (most recent call last):
File "C:\Users\ryry3\Desktop\Python Projects\Games\Pygame Experiment\Sprint2.py", line 65, in <module>
resetBoard()
File "C:\Users\ryry3\Desktop\Python Projects\Games\Pygame Experiment\Sprint2.py", line 49, in resetBoard
if board[i][j] != 0:
IndexError: list index out of range
Here is my full code:
import random
grid = [100,100]
board = [[0,0,0,0,0,0,1,0,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,0,0,0,0,0,1,0,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,0,0,5,0,0,0,0,0,0],
[0,0,0,0,0,0,0,0,0,0]]
playerX = None
playerY = None
randX = 0
randY = 0
def getRandomGridPos():
global randX, randY
randX = int(random.uniform(0, grid[0]))
randY = int(random.uniform(0, grid[1]))
def main():
pass
def printBoard():
print str(board[0]).replace(',', '')
print str(board[1]).replace(',', '')
print str(board[2]).replace(',', '')
print str(board[3]).replace(',', '')
print str(board[4]).replace(',', '')
print str(board[5]).replace(',', '')
print str(board[6]).replace(',', '')
print str(board[7]).replace(',', '')
print str(board[8]).replace(',', '')
print str(board[9]).replace(',', '')
def resetBoard():
i = 0
j = 0
while i < 10:
if board[i][j] != 0:
board[i][j] = 0
j += 1
print "Looping"
if j == 10:
j = 0
i += 1
print "J == 10"
if i == 10:
j = 0
i = 0
print "I == 10"
else:
j += 1
resetBoard()
Can someone help me find a solution and also help me not get this error anymore (explain why it happens)?

Answer 1

You've already gotten several pointers to the cause of your error, but I just wanted to point out a clearer pattern to iterate multi-dimensional arrays:
for x in range(0, 10):
for y in range(0, 10):
# you will now have all values for a 10x10 array in x & y
if board[x][y] != 0:
board[x][y] = 0
If you really just want to make sure all board fields (10 x 10) are zeros, the following is even more consice:
# zero out a 10 x 10 multi-dimensional array
board = [[0] * 10] * 10

Answer 2

Your for reset board doesn't work for the following reasons:
"if i == 10" ,i never actually reaches 10, since it is in a while loop which states "while i < 10". The loop would exit before i actually reaches 10
no nested while loop. You need two while loops to reset the board.
When j reaches 10 this line raises an index error: if board[i][j] != 0: , because j equals 10, and the maximum index you can take of a 10 element list is 9(since index starts at 0)
I recommend reading the following
http://introtopython.org/lists_tuples.html
I would add that one of the best ways to achieve what you want in python with loops is:
for row in board: # runs the following once for every item in board
for item in row: # runs the following for every item in row.
# A second for statement is required because
# multidimensional lists are lists of lists.
if(item != 0)
item = 0 #sets items to 0 if the item isn't equal to 0

Answer 3

UPDATE:
Sorry but I also encoutered another problem, my bad for not checking the code:
The final code should be:
while i < 10:
if j == 10:
j = 0
i += 1
print ("J == 10")
elif board[i][j] != 0:
board[i][j] = 0
j += 1
print ("Looping")
else:
j += 1
The problem I missed was that you should have checked the j boundary before trying to access the array, only then you should start the loop again.
The problem is in this part:
if j == 10:
j = 0
i += 1
print "J == 10"
if i == 10:
j = 0
i = 0
if i = 9, j= 10 then we enter into the first if which changes i,j to be 10,10
Then the code continues and we enter the second if, thus reseting i and j making the loop go again and again...
Solve it by deleting the second if part, since the while condition will make sure we will never go to that case in the first place.