将对象添加到字典中的现有值

Question

In order to make my own tile based rpg, I have a question. I have a dictionary where I want, during the creation of my tile map, to store pairs of tile type/ rect values eg

{1: rect(0, 0, 32, 32), 2: rect(0, 32, 32, 32)}

My problem now is that I have to give every key multiple values, since there is only a limited number of tile types but multiple tiles of each type. So I tried this:

def create(self):
    x, y = 0, 0
    for row in self.matrix:
        for tile in row:
            self.surface.blit(tiles[int(tile)].img, (x-camerax, y-cameray))
            tiles[int(tile)].rect = pygame.Rect(x-camerax, y-cameray, 32, 32)
            if numbers[tiles[int(tile)]] not in collision_list:
                collision_list[numbers[tiles[int(tile)]]] = tiles[int(tile)].rect
            else:
                dummytuple = collision_list[numbers[tiles[int(tile)]]]
                collision_list[numbers[tiles[int(tile)]]] = dummytuple, tiles[int(tile)].rect
            x += 32
            if x >= self.surface.get_width():
                y += 32
                x = 0

Might be a bit complicated since I'm not very good at writing simple code. My problem is in the if else statements. I use them to check whether one type of tile in the dictionary collide_list already has one or multiple rects assigned. If so, the existing rect should be added as a second value to the key. This kind of works, but prints out this in the shell:

(((((((((((((((((((((((((((<rect(0, 0, 32, 32)>, <rect(32, 0, 32, 32)>), <rect(64, 0, 32, 32)>), <rect(96, 0, 32, 32)>), <rect(128, 0, 32, 32)>), <rect(160, 0, 32, 32)>), <rect(192, 0, 32, 32)>), <rect(224, 0, 32, 32)>), <rect(256, 0, 32, 32)>), <rect(288, 0, 32, 32)>), <rect(320, 0, 32, 32)>), <rect(352, 0, 32, 32)>), <rect(384, 0, 32, 32)>), <rect(416, 0, 32, 32)>), <rect(448, 0, 32, 32)>), <rect(0, 32, 32, 32)>), <rect(160, 32, 32, 32)>), <rect(192, 32, 32, 32)>), <rect(224, 32, 32, 32)>), <rect(256, 32, 32, 32)>), <rect(288, 32, 32, 32)>), <rect(320, 32, 32, 32)>), <rect(352, 32, 32, 32)>), <rect(384, 32, 32, 32)>), <rect(416, 32, 32, 32)>), <rect(448, 32, 32, 32)>), <rect(0, 64, 32, 32)>), <rect(32, 64, 32, 32)>)

This is only for one key (sorry for spamming). This is VERY complicated to read and very hard to work with later on. Isn't there a better possibility of concatenating a value to an existing value in a dictionary? Any help is appreciated.

Answer 1

You are collecting the existing tuple, then creating a new tuple with that existing tuple nested into it:

dummytuple = collision_list[numbers[tiles[int(tile)]]]
collision_list[numbers[tiles[int(tile)]]] = dummytuple, tiles[int(tile)].rect

Instead, append a new one-element tuple:

dummytuple = collision_list[numbers[tiles[int(tile)]]]
collision_list[numbers[tiles[int(tile)]]] = dummytuple + (tiles[int(tile)].rect,)

You certainly should leave your one-element values to be just a rectangle, start with a one-element tuple:

if numbers[tiles[int(tile)]] not in collision_list:
    collision_list[numbers[tiles[int(tile)]]] = (tiles[int(tile)].rect,)
else:
    dummytuple = collision_list[numbers[tiles[int(tile)]]]
    collision_list[numbers[tiles[int(tile)]]] = dummytuple + (tiles[int(tile)].rect,)

or, much better still, use a list, you are after all altering it constantly:

if numbers[tiles[int(tile)]] not in collision_list:
    collision_list[numbers[tiles[int(tile)]]] = [tiles[int(tile)].rect]
else:
    collision_list[numbers[tiles[int(tile)]]].append(tiles[int(tile)].rect)

If you make collision_list a collections.defaultdict object you don't even have to test for the key first:

from collections import defaultdict

collision_list = defaultdict(list)

# ....

# No `if numbers[tiles[int(tile)]] not in collision_list` needed
collision_list[numbers[tiles[int(tile)]]].append(tiles[int(tile)].rect)