2d class member list of objects not updating

[Xillez]

I have a problem updating self.tiles[][].type in line 29. Once leaving the for loops in Map's __init__, the tiles list "forgets" the update somehow.

- I've tried adding a setter function for "type" in Tile but that didn't work also tried making the "type" a class level variable but that didn't and wouldn't help anyway.
- I don't suspect its something to do with reference since I'm only working on the instances and never go to the class for any variables.
- It might be that the tiles array in map doesn't contain instances in the way I think they do, but idk.

Would appreciate if anyone tell me why it doesn't update the tiles list after the for loops in __init__.

(debugging print's included)

import tkinter as tk
from tkinter import *
 
class Tile:
    def __init__(self, type, pos = (0, 0), isPath = False): #, cost):
        self.type = type
        self.pos = pos
        self.isPath = isPath
        #self.cost = cost
 
    def getColor(self):
        if (self.isPath):           # Tile is a part of path
            return "red"
        elif (self.type == "."):    # Traversable tile
            return "white"
        elif (self.type == "#"):    # Intraversable tile
            return "brown"
 
class Map:
    def __init__(self, filename):
        self.width = len(open(filename, "r").readline()) - 1            # Find size of first line
        self.height = sum(1 for line in open(filename))                 # Find nr of lines
        self.tiles = [[Tile(".")] * self.width] * self.height           # Ready tile
 
        print("Map.tiles 2d list content:")
 
        with open(filename, "r") as f:                                  # Open given file
            print("Updating in __init__:")
            for y, line in enumerate(f):                                # For every line
                for x, letter in enumerate(line):                       # For every letter
                    if (letter != "\n"):                                # Ignore newline
                        self.tiles[y][x].type = letter                  # Update tile type
                        print(self.tiles[y][x].type, end = "")
                        self.tiles[y][x].pos = (x, y)                   # Tell tile where it is on map
                        if (letter == "A"):                             # Save start index
                            self.start = (x, y)
                        elif (letter == "B"):                           # Save goal index
                            self.goal = (x, y)
                print("")
            print("")
 
            print("Just after updating in __init__:")
            for row in self.tiles:
                for tile in row:
                    print(tile.type, end = "")
                print("")
        print("")
 
    def AStar(self, start, goal):
        print("")
 
    def drawMap(self, canvas):
        print("When displaying on screen in drawMap:")
        tileDim = (canvas.winfo_width() / self.width, canvas.winfo_height() / self.height)  # Find tile size
        for y, row in enumerate(self.tiles):                                                # For every row
            for x, tile in enumerate(row):                                                   # For every column in said row
                canvas.create_rectangle(tileDim[0] * x,                                     # Draw tile
                                        tileDim[1] * y, 
                                        (tileDim[0] * x) + tileDim[0], 
                                        (tileDim[1] * y) + tileDim[1], 
                                        fill = tile.getColor())
                print(tile.type, end = "")
            print("")
 
root = tk.Tk()
root.title("A* Pathfinding")
root.geometry("720x480")
 
canvas = tk.Canvas(root, width = root.winfo_width(), height = root.winfo_height())
canvas.pack(side="top", fill = "both", expand = True)
canvas.update()
 
obj = Map("./boards/board-1-1.txt")
obj.drawMap(canvas)
 
root.mainloop()
 

Output (terminal):

Map.tiles 2d list content:
Updating in __init__:
....................
....................
.........######.....
...........A..#..B..
.........######.....
....................
....................
 
Just after updating in __init__:
....................
....................
....................
....................
....................
....................
....................
 
When displaying on screen in drawMap:
....................
....................
....................
....................
....................
....................
....................
 

[dwblas]

Some simple print statements should show the problem. For example

self.tiles[y][x].type = letter
print(self.tiles[y][x])
 
## this should likely be
self.tiles[y][0][0].type
""" as the class instance is in the first position,
 offset=0, of the sub-list, and the first/only position
 in that sub-list.  print() self.tiles[y][0][0] and/or 
 self.tiles[y][0][0].type to test for yourself
 self.tiles = [[Tile(".")] * self.width] * self.height
"""
 
## A dictionary would work better here IMHO
self.tiles={}
self.tiles[Tile(".")]=self.width] * self.height           
 

[Xillez]

Appreciate the answer but...

I tried printing with self.tiles[y][0][0] with and without .type and it says "Tile object does not support indexing". The [][][] tries to fetch the a position within a 3d list, but since [[] * width] * height makes a 2d list this is understandable, so the object lies in the inner list.

As far as I understand the code should be correct (coming from a c++/java programming background, which of course doesn't mean that python behaves the same)

But the main problem is that the the 2d list "tiles" looses it's updated state once exiting the for loops updating them (in __init__). I have a print out within the same function and yet it prints only dots... so I suspect it might be something with the self and it not being a Tile object but something else, OR, it might be something with the list (or the initialization of it) that doesn't allow me to update them.

[Xillez]

Solved it by making the "self." variables in Map global using the "global" key word (and removing the "self." of course). It might not be a good thing, but it works