Question

I’m making a water simulation program, and I need it to do a for loop through y, x. But I need it to check the most bottom y first, then up. This is my lvl:

lvl = [[0, 0, 1, 0, 0],
       [0, 0, 1, 0, 0],
       [0, 0, 1, 0, 0],
       [0, 0, 0, 0, 0],
       [0, 0, 0, 0, 0]]

I need it to check lvl[4] and then lvl[3], lvl[2], etc. Please help!

NB: I’m using nested for loops, so I can check y, x.

Answer 1

You can use the reversed built-in method to reverse the ordering of your list of lists:

for li in reversed(lvl):
    print li

Output:

[0, 0, 0, 0, 0]
[0, 0, 0, 0, 0]
[0, 0, 1, 0, 0]
[0, 0, 1, 0, 0]
[0, 0, 1, 0, 0]