How to randomize all the colors to different colors every time the snake eats and grows?

Question

I'm new to python and am making snake for a project/ I'm not sure how to randomize all the colors to different colors every time the snake eats and grows. I've looked up multiple things and nothing has worked.

Answer 1

Keep colors in variables like

snake_head_color = 'red' 
snake_tail_color = 'green'

In main loop use these variables to draw objects like

    # draw head    
    pygame.draw.rect(screen, snake_head_color, (100, 100, 48, 48))
    
    # draw tail
    for x in range(150, 700, 50):
        pygame.draw.rect(screen, snake_tail_color, (x, 100, 48, 48))

And later you can use random.choice(list) to assign new colors when it grows.

snake_head_color = random.choice(['red', 'yellow', 'gray50'])
snake_tail_color = random.choice(['green', 'blue', 'gray25'])

This way it will draw snake using new colors.

---

Minimal working code. It changes colors when you use mouse button (or wheel)

import pygame
import random

# === constants ===  # PEP8: UPPER_CASE_NAMES

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

FPS = 60
FPS = 120

BLACK = (0, 0, 0)
WHITE = (255, 255, 255)

# === classes ===  # PEP8: CamelCaseNames

# empty

# === functions ===  # PEP8: lower_case_names

# empty

# === main ===

pygame.init()

screen = pygame.display.set_mode( (SCREEN_WIDTH, SCREEN_HEIGHT) )

# set some color at start 
snake_head_color = 'red'
snake_tail_color = 'green'

change_colors = False

# --- mainloop ---

clock = pygame.time.Clock()

running = True

while running:

    # --- events ---
    
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        elif event.type == pygame.KEYUP:
            if event.key == pygame.K_ESCAPE:
                running = False

        elif event.type == pygame.MOUSEBUTTONDOWN:
            change_colors = True

    # --- changes/moves/updates ---

    if change_colors:
        # select random color
        snake_head_color = random.choice(['red', 'yellow', 'gray50'])  # select new color
        snake_tail_color = random.choice(['green', 'blue', 'gray25'])  # select new color

        change_colors = False
        
    # --- draws ---

    screen.fill(BLACK)

    # draw head    
    pygame.draw.rect(screen, snake_head_color, (100, 100, 48, 48))
    
    # draw tail
    for x in range(150, 700, 50):
        pygame.draw.rect(screen, snake_tail_color, (x, 100, 48, 48))
    
    pygame.display.flip()

    # --- FPS ---

    dt = clock.tick(FPS) 
    #pygame.display.set_caption(f'{dt:.2f} ms')
    
# --- end ---

pygame.quit()

---

Because it always select new color from the same list so sometimes it may select exactly the same color as current color - and it may seen like it doesn't select color. But you can remove current color from list before select new color.

    # --- changes/moves/updates ---

    if change_colors:
        color = ['red', 'yellow', 'gray50']       # create list with all colors
        color.remove(snake_head_color)            # remove current color
        snake_head_color = random.choice(color)   # select new color

        color = ['green', 'blue', 'gray25']       # create list with all colors
        color.remove(snake_tail_color)            # remove current color
        snake_tail_color = random.choice(color)   # select new color
        
        change_colors = False

BTW:

Previous version needs to create new local list with all colors in every loop.
If you want to keep lists in global variables then it may need to create local copy (using list.copy()).

# --- constants --- (UPPER_CASE_NAMES)

SNAKE_HEAD_ALLOWED_COLORS = ['red', 'yellow', 'gray50']
SNAKE_TAIL_ALLOWED_COLORS = ['green', 'blue', 'gray25']

    # ... later ...

    # --- changes/moves/updates ---

    if change_colors:
        color = SNAKE_HEAD_ALLOWED_COLORS.copy()  # create list with all colors (it needs `copy()`)
        color.remove(snake_head_color)            # remove current color
        snake_head_color = random.choice(color)   # select new color

        color = SNAKE_TAIL_ALLOWED_COLORS.copy()  # create list with all colors (it needs `copy()`)
        color.remove(snake_tail_color)            # remove current color
        snake_tail_color = random.choice(color)   # select new color
        
        change_colors = False

Eventually you could use list comprehension to select all colors except current color

# --- constants --- (UPPER_CASE_NAMES)

SNAKE_HEAD_ALLOWED_COLORS = ['red', 'yellow', 'gray50']
SNAKE_TAIL_ALLOWED_COLORS = ['green', 'blue', 'gray25']

    # ... later ...

    # --- changes/moves/updates ---

    if change_colors:

        color = [x for x in SNAKE_HEAD_ALLOWED_COLORS if x != snake_head_color]
        snake_head_color = random.choice(color)   # select new color

        color = [x for x in SNAKE_TAIL_ALLOWED_COLORS if x != snake_tail_color]
        snake_tail_color = random.choice(color)   # select new color

        change_colors = False