CODEWITHSUNDEEP
pythonpygame
Duck McFuddle
Duck McFuddle

Reputation: 27

ValueError: not enough values to unpack (expected 4, got 3)

I've got some code that currently displays a random number of randomly coloured rectangles at random points around the screen. Now, I want to make them move randomly. I have a for loop that is generating the random colours, x, y, etc. and also the direction that the squares will move in. Further down in my code, I have another for loop (this one contained within the main game loop) that displays the squares and interprets the random direction so they can move. However, when I try to run the program, it gives me the error described in the title. What am I doing wrong?

randpop = random.randint(10, 20)

fps = 100

px = random.randint(50, 750)
py = random.randint(50, 750)
pxp = px + 1
pyp = py + 1
pxm = px - 1
pym = py - 1
moves_list = [pxp, pyp, pxm, pym]

population = []
for _ in range(0, randpop):
    pcol = random.choice(colour_list)
    px = random.randint(50, 750)
    py = random.randint(50, 750)
    direction = random.choice(moves_list)
    population.append((px, py, pcol))

[...]

while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    screen.fill(GREY)

    for px, py, pcol, direction in population:
        pygame.draw.rect(screen, pcol, (px, py, 50, 50))

        print(direction)
        if direction == pxp:
            px += 1
        if direction == pyp:
            py += 1
        if direction == pxm:
            px -= 1
        if direction == pym:
            py -= 1

    pygame.display.update()

Upvotes: 1

Views: 5727

Answers (2)

Rabbid76
Rabbid76

Reputation: 210909

In the for-loop you expect that the tuple size is 4:

for px, py, pcol, direction in population:

But when you set up the list of tuples, then you have forgotten direction, so the tuple size is just 3. This causes the error.
Add direction to the tuple:

population.append((px, py, pcol))

population.append((px, py, pcol, direction))

If you want to make the rectangles move, then you've to update the data in the list. e.g.:

for i, (px, py, pcol, direction) in enumerate(population):

    pygame.draw.rect(screen, pcol, (px, py, 50, 50))

    print(direction)
    if direction == pxp:
        px += 1
    if direction == pyp:
        py += 1
    if direction == pxm:
        px -= 1
    if direction == pym:
        py -= 1

    population[i] = (px, py, pcol, direction)

Upvotes: 1

memolad
memolad

Reputation: 1

This line is the cause of the issue:

for px, py, pcol, direction in population:
    pygame.draw.rect(screen, pcol, (px, py, 50, 50))

And if you look before that, this is actually the real problem:

population.append((px, py, pcol))

I assume you wanted to type population.append((px, py, pcol, direction))

Upvotes: 0

Related Questions