Suggested change to demo Life program

[ideonaut]

The existing Life program on the site gets weird when things reach the edges. To get traditional toroidal wrapping, I suggest:

        for dy in range(-1, 2):
            ny = (y + dy) % grid_y_count # line added
            for dx in range(-1, 2):
                nx = (x + dx) % grid_x_count # line added
                if (not (dy == 0 and dx == 0)
                    and grid[ny][nx]): # line added

# lines removed: # and (y + dy) < len(grid) # and (x + dx) < len(grid[y + dy]) # and grid[y + dy][x + dx]):

                    neighbor_count += 1

Of course the new variables ny and nx aren't really necessary, but they helped me figure out the fix and may make it more readable.

[lordmauve]

Which demo is this? I don't think we have a Conway's Life demo.

[ideonaut]

That's embarrassing! I got it from https://simplegametutorials.github.io/pygamezero/life/ , which I thought was part of the Pygame Zero site... Guess not!

I'll go bother them now.