Turn With the Arrows

Lesson 21 of 40 in Coddy's Make Games with Pygame course.

A snake turns once per key press, so read the arrows from KEYDOWN events. A dictionary maps each arrow key to its direction:

TURNS = {
    pygame.K_LEFT: (-1, 0),
    pygame.K_RIGHT: (1, 0),
    pygame.K_UP: (0, -1),
    pygame.K_DOWN: (0, 1),
}

event.key in TURNS is true for the four arrows, and TURNS[event.key] is the new direction. One test replaces four if statements:

elif event.type == pygame.KEYDOWN and event.key in TURNS:
    direction = TURNS[event.key]

Up is (0, -1): rows count down the window, like pixels.

Challenge

Easy

Above pygame.init(), add the TURNS dictionary for the four arrows.
In the event loop, when a KEYDOWN event's key is in TURNS, set direction to its value.

Try it yourself

import pygame

CELL = 20
COLS, ROWS = 24, 18

pygame.init()
screen = pygame.display.set_mode((COLS * CELL, ROWS * CELL))
pygame.display.set_caption("Snake")
clock = pygame.time.Clock()


def draw_cell(cell, color):
    col, row = cell
    pygame.draw.rect(screen, color, (col * CELL + 1, row * CELL + 1, CELL - 2, CELL - 2))


head = (5, 9)
direction = (1, 0)

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

    head = (head[0] + direction[0], head[1] + direction[1])

    screen.fill((30, 30, 46))
    draw_cell(head, (180, 255, 160))
    pygame.display.flip()
    clock.tick(10)

pygame.quit()