How to move the player upwards and downwards?

[Windspar]

1. You can use pygame.Vector2 over pygame.math.Vector2.

Example how I do it. Using pure Vector2 math.

import os
import pygame
from pygame.sprite import Group, Sprite

class Engine:
    @staticmethod
    def center_screen():
        os.environ['SDL_VIDEO_CENTERED'] = '1'

    def __init__(self, caption, width, height, flags=0):
        pygame.display.set_caption(caption)
        self.surface = pygame.display.set_mode((width, height), flags)
        self.rect = self.surface.get_rect()
        self.clock = pygame.time.Clock()
        self.running = False
        self.delta = 0
        self.fps = 60

    def idle(self):
        self.delta = self.clock.tick(self.fps)

    def quit(self):
        self.running = False

class SimpleSprite(Sprite):
    def __init__(self, image, position, anchor="topleft"):
        Sprite.__init__(self)
        self.image = image
        self.rect = self.image.get_rect(**{anchor: position})

class Movement:
    def __init__(self, sprite, speed, angle=180):
        self.sprite = sprite
        self.speed = speed * 0.01
        self.original_image = sprite.image
        self.velocity = pygame.Vector2(0, 0)
        self.center = pygame.Vector2(sprite.rect.center)
        self.rotation_speed = 8 * 0.01

        self.angle = angle
        self.vector = self.get_vector()
        self._move = None
        self._rotate = None

    def get_vector(self):
        vector = pygame.Vector2(0, 0)
        vector.from_polar((1, self.angle))
        vector.x, vector.y = vector.y, vector.x
        return vector

    def up_action(self):
        self._move = self.move_up

    def down_action(self):
        self._move = self.move_down

    def left_action(self):
        self._rotate = self.rotate_left

    def right_action(self):
        self._rotate = self.rotate_right

    def move_up(self, delta):
        self.center += self.vector * self.speed * delta
        self.sprite.rect.center = self.center

    def move_down(self, delta):
        self.center += -self.vector * self.speed * delta
        self.sprite.rect.center = self.center

    def rotate_left(self, delta):
        self.angle = (self.angle + self.rotation_speed * delta) % 360
        self.update_rotation()

    def rotate_right(self, delta):
        self.angle = (self.angle - self.rotation_speed * delta) % 360
        self.update_rotation()

    def update_rotation(self):
        self.sprite.image = pygame.transform.rotate(self.original_image, self.angle)
        self.sprite.rect = self.sprite.image.get_rect(center=self.center)
        self.vector = self.get_vector()

    def move(self, delta):
        if self._rotate:
            self._rotate(delta)

        if self._move:
            self._move(delta)

        self._move = None
        self._rotate = None

class MovementKeys:
    def __init__(self, movement, up, down, left, right):
        self.movement = movement
        self.up = self.wrap(up)
        self.down = self.wrap(down)
        self.left = self.wrap(left)
        self.right = self.wrap(right)

    def update(self, delta, keys_pressed):
        keys = lambda pressed, key: any(pressed[k] for k in key)
        if keys(keys_pressed, self.up):
            self.movement.up_action()

        if keys(keys_pressed, self.down):
            self.movement.down_action()

        if keys(keys_pressed, self.right):
            self.movement.right_action()

        if keys(keys_pressed, self.left):
            self.movement.left_action()

        self.movement.move(delta)

    def wrap(self, item):
        if isinstance(item, list):
            return item
        elif isinstance(item, tuple):
            return list(item)
        else:
            return [item]

class Player:
    def __init__(self, rect):
        image = pygame.Surface((20, 20), pygame.SRCALPHA)
        image.fill(pygame.Color('dodgerblue'))

        self.sprite = SimpleSprite(image, rect.center, "center")
        self.movement = Movement(self.sprite, 8)
        self.movement_keys = MovementKeys(self.movement,
                                          (pygame.K_UP, pygame.K_w),
                                          (pygame.K_DOWN, pygame.K_s),
                                          (pygame.K_LEFT, pygame.K_a),
                                          (pygame.K_RIGHT, pygame.K_d))

    def update(self, delta, keys_pressed):
        self.movement_keys.update(delta, keys_pressed)

class Scene:
    def __init__(self, engine):
        self.engine = engine
        self.background = pygame.Color("black")
        self.player = Player(engine.rect)
        self.sprites = Group(self.player.sprite)

    def on_draw(self, surface):
        surface.fill(self.background)
        self.sprites.draw(surface)

    def on_event(self):
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                self.engine.quit()

    def mainloop(self):
        self.engine.running = True
        while self.engine.running:
            self.on_event()
            self.on_update(self.engine.delta)
            self.on_draw(self.engine.surface)
            pygame.display.flip()
            self.engine.idle()

    def on_update(self, delta):
        keys_pressed = pygame.key.get_pressed()
        self.player.update(delta, keys_pressed)

def main():
    pygame.init()
    Engine.center_screen()
    engine = Engine("Movement Example", 600, 600)
    scene = Scene(engine)
    scene.mainloop()

main()