Python Forum

Basically, I'm just trying to understand the logic for the nested loop inputs and outputs. The first nested loops seems to append either a # or a space for 20 values 60 times. So, I understand that I'm inputting either a # or space 20 times per row? What confuses me is the second nested for loop. The WIDTH and HEIGHT are inverted. You start off X with width and then y with height. I don't understand this. In my second nested loop I tried to make the range of the outer loop WIDTH and the inner HEIGHT, but I get an indexing error but I don't understand why? I'm just using the same indexing I used in the previous? How come I have to invert the WIDTH AND HEIGHT for the second nested loop?

WIDTH = 60
HEIGHT = 20

nextCells = []
for x in range(WIDTH):
    column = []
    for y in range(HEIGHT):
        if random.randint(0,1):
            column.append('#')
        else:
            column.append(' ')
    nextCells.append(column)

while True:
    print('\n\n\n\n\n')
    currentCells = copy.deepcopy(nextCells)

    for y in range(HEIGHT):
        for x in range(WIDTH):
            print(currentCells[x][y],end='')
        print()

To match the first for loops the second loops should be

for x in range(WIDTH):
    for y in range(HEIGHT):

not

for y in range(HEIGHT):
    for x in range(WIDTH):

Also, note you would probably want the inner loop to be the WIDTH and the outer loop to be the HEIGHT

I see, although not quite. After reviewing how these lists interacted with these nested loops I'm more confused. I'm coming from C++ and I know that arrays are used for stuff like this but it seems different. I don't see why accessing a list would require an x and y since it doesn't seem to be a multidimensional list. Then again I have no idea.

(Aug-04-2020, 06:59 AM)Morte Wrote: [ -> ]since it doesn't seem to be a multidimensional list.

Assuming "it" is currentCells, why do you think that? It's a copy of nextCells and nextCells appears to be a multidimensional list (really just a list of lists).

Now I see what I was doing wrong. I looked over how deepcopy was working and treated it like an array instead of a list so I need to review more. Thank you for bringing the list of list up. Now wonder I was indexing incorrectly.