Python Drawing ASCII Map

Question

I need to have a 2 radius map drawn off the player's current room in a MUD I'm building in python (or more, if possible). Rooms are set up as containers with a self.exits = {'west':1, 'north':2} where the key is the direction that the value (UID of the adjacent room) is located. Rooms are linked only in this way. A player with a self.location of 0 could type 'n' and their location, based on the above variable, would then be 2 and that room's contents would have the player's UID appended to its contents.

So, I would like to have a map displayed that looks like the following, based on the above variable, where 'u' is the player's current location..

    [ ]
     |
[ ]-[u]

I've achieved this portion, as this is just a radius of 1. Here is a small (heavily modified for posting here) snippet of how I did this, and you'll see why I'm posting, as it's poor code.

mloc = '[u]'
mn = '   '
mw = '   '
spn= ' '
spw= ' '
for Exit in room.exits.keys():
  if Exit == 'north':
    mn = '[ ]'
    spn = '|'
  if Exit == 'west': 
    mw = '[ ]-'
# player.hear() is our function for printing a line to the player's screen
player.hear('    '+mn)
player.hear('     '+sp)
player.hear(mw+mloc)

In my insanity, I managed to make this work with all 8 different directions (diagonals, and not including up or down). But I then have to for loop the rooms I just parsed with my first for loop, and then draw those, and then space it all out, and then take into account the overlap of the (sp)aces such as '\' or '|' if there are paths that cross each other. This small task turned nightmarish immediately, and well into 200 lines before I was done.

Another hurdle is that I can only print line by line. So if the map is 50 characters high, I have to have player.hear() on 50 lines, which I'm not opposed to. Just keep that in mind before posting an answer.

I'm also not picky about formatting. I just simply want a 'map at a glance' to aid players while traveling around the world.

Thanks guys. I hope I provided enough info. Let me know, if not. (Here is a link to the entire (unfinished and HORRIBLE) module I'm referencing. Map.py

Answer 1

This code is in serious trouble. Let's start designing from scratch. This will hopefully serve as a good lesson in how to design and build classes and data structures.

To start with, you should organize your code around a Map class, which then represents your rooms as a grid. You shouldn't think about "room 1", "room 2", etc (which is very hard to keep track of on a map), and rather think of rooms in terms of coordinates.

Now, there are a few possible features we are ignoring at the beginning, including the player seeing only rooms he's been to, the player remaining at the center of the map, and diagonal paths. If you want them you can put them in later, once the basic functionality works. For now, we are aiming for something that looks a little like this:

[ ]-[u] [ ] [ ]
 |
[ ]-[ ]-[ ] [ ]
     |
[ ]-[ ]-[ ] [ ]
 |
[ ]-[ ]-[ ]-[ ]

That is, we're representing it as a grid where some rooms are connected and others are not. Let's have each room have a coordinate pair, a little like this:

      0   1   2   3
   0 [ ]-[u] [ ] [ ]
      |
   1 [ ]-[ ]-[ ] [ ]
          |
   2 [ ]-[ ]-[ ] [ ]
      |
   3 [ ]-[ ]-[ ]-[ ]

Let x be along the top and y be along the side. The top left is (0, 0), the one with [u] in it is (0, 1).

Now, what are the components of our Map class?

1. map height: integer

2. map width: integer)

3. player_x, player_y: coordinates of player

4. possible paths: a list of pairs of rooms that we can move between. The above map would be represented as:

   [((0, 0), (1, 0)), ((0, 0), (1, 0)), ((1, 0), (1, 1)), ((1, 1), (2, 1)),
    ((1, 0), (1, 2)), ((0, 2), (1, 2)), ((1, 2), (2, 2)), ((0, 2), (0, 3)),
    ((0, 3), (1, 3)), ((1, 3), (2, 3)), ((2, 3), (3, 3))]
   

Notice that I ordered each pair such that the larger tuple goes first (that's important later).

So now that we have our design, let's write that Map class!

I can think of four methods we want: print_map, move, and an initializer. Intitialization is simple: just set the four attributes we listed above:

class Map:
    def __init__(self, height, width, player_x, player_y, paths):
        self.height = height
        self.width = width
        self.x = player_x
        self.y = player_y
        self.paths = paths

Now, move is quite simple. Given a direction n/e/s/w:

    def move(self, direction):
        if direction == "n":
            if ((self.x, self.y - 1), (self.x, self.y)) not in self.paths:
                print "Cannot go north"
            else:
                self.y -= 1

The move function for "north" just checks if there is a path to the room above the one we are in.

Now for the most interesting part: printing the map. You do this by looping over the rows (0 to self.height) and over the columns (0 to self.width). (Note: you can't use print in this situation since it automatically puts a newline or space after the string. Instead we use sys.stdout.write.

def print_map(self):
    for y in range(0, self.height):
        # print the yth row of rooms
        for x in range(0, self.width):
            if self.x == x and self.y == y:
                sys.stdout.write("[u]")  # this is the player's room
            else:
                sys.stdout.write("[ ]")  # empty room
            # now see whether there's a path to the next room
            if ((x, y), (x + 1, y)) in self.paths:
                sys.stdout.write("-")
            else:
                sys.stdout.write(" ")
        # now that we've written the rooms, draw paths to next row
        print  # newline
        for x in range(0, self.width):
            sys.stdout.write(" ")  # spaces for above room
            if ((x, y), (x, y + 1)) in self.paths:
                sys.stdout.write("|  ")
            else:
                sys.stdout.write("   ")
        print

Now, let's put it all together and try it out. Here's the code:

import sys

class Map:
    def __init__(self, height, width, player_x, player_y, paths):
        self.height = height
        self.width = width
        self.x = player_x
        self.y = player_y
        self.paths = paths

    def move(self, direction):
        if direction == "n":
            if ((self.x, self.y - 1), (self.x, self.y)) not in self.paths:
                print "Cannot go north"
            else:
                self.y -= 1
        if direction == "s":
            if ((self.x, self.y), (self.x, self.y + 1)) not in self.paths:
                print "Cannot go south"
            else:
                self.y += 1
        if direction == "e":
            if ((self.x, self.y), (self.x + 1, self.y)) not in self.paths:
                print "Cannot go east"
            else:
                self.x += 1
        if direction == "w":
            if ((self.x - 1, self.y), (self.x, self.y)) not in self.paths:
                print "Cannot go west"
            else:
                self.x -= 1

    def print_map(self):
        for y in range(0, self.height):
            # print the yth row of rooms
            for x in range(0, self.width):
                if self.x == x and self.y == y:
                    sys.stdout.write("[u]")  # this is the player's room
                else:
                    sys.stdout.write("[ ]")  # empty room
                # now see whether there's a path to the next room
                if ((x, y), (x + 1, y)) in self.paths:
                    sys.stdout.write("-")
                else:
                    sys.stdout.write(" ")
            # now that we've written the rooms, draw paths to next row
            print  # newline
            for x in range(0, self.width):
                sys.stdout.write(" ")  # spaces for above room
                if ((x, y), (x, y + 1)) in self.paths:
                    sys.stdout.write("|  ")
                else:
                    sys.stdout.write("   ")
            print


paths = [((0, 0), (1, 0)), ((0, 0), (1, 0)), ((1, 0), (1, 1)), ((1, 1),
         (2, 1)), ((1, 1), (1, 2)), ((0, 2), (1, 2)), ((1, 2), (2, 2)),
         ((0, 2), (0, 3)), ((0, 3), (1, 3)), ((1, 3), (2, 3)), ((2, 3),
         (3, 3))]
m = Map(4, 4, 0, 0, paths)

while True:
    m.print_map()
    direction = raw_input("What direction do you want to move? [n/e/s/w] ")
    m.move(direction)

Notice that I added a section on the bottom that creates a map and allows the player to move around it. Here's how it looks when it runs:

Davids-MacBook-Air:test dgrtwo$ python Map.py 
[u]-[ ] [ ] [ ] 
     |          
[ ] [ ]-[ ] [ ] 
     |          
[ ]-[ ]-[ ] [ ] 
 |              
[ ]-[ ]-[ ]-[ ] 

What direction do you want to move? [n/e/s/w] e
[ ]-[u] [ ] [ ] 
     |          
[ ] [ ]-[ ] [ ] 
     |          
[ ]-[ ]-[ ] [ ] 
 |              
[ ]-[ ]-[ ]-[ ] 

What direction do you want to move? [n/e/s/w] s
[ ]-[ ] [ ] [ ] 
     |          
[ ] [u]-[ ] [ ] 
     |          
[ ]-[ ]-[ ] [ ] 
 |              
[ ]-[ ]-[ ]-[ ] 

What direction do you want to move? [n/e/s/w] w
Cannot go west
[ ]-[ ] [ ] [ ] 
     |          
[ ] [u]-[ ] [ ] 
     |          
[ ]-[ ]-[ ] [ ] 
 |              
[ ]-[ ]-[ ]-[ ] 

What direction do you want to move? [n/e/s/w] e
[ ]-[ ] [ ] [ ] 
     |          
[ ] [ ]-[u] [ ] 
     |          
[ ]-[ ]-[ ] [ ] 
 |              
[ ]-[ ]-[ ]-[ ] 

There are many improvements that can be made to this code (in particular, the move method is repetitive), but it's a good start. Try making the map 20x20 and you'll see it expands just fine.

ETA: I should note that print_map could be rewritten in a much shorter form as something like:

def print_map(self):
    for y in range(0, self.height):
        print "".join(["[%s]%s" %
                    ("u" if self.x == x and self.y == y else " ",
                     "-" if ((x, y), (x + 1, y)) in self.paths else " ")
                        for x in range(0, self.width)])
        print " " + "   ".join(["|" if ((x, y), (x, y + 1)) in self.paths
                              else " " for x in range(0, self.width)])

But this is a bit more intense.

Answer 2

I did this as an exercise where the rooms and the grid "print themselves". I add this to the discussion as it may be easier to implement with an eventual larger grid.

The ASCII Map

+++++++++++++++
+++++++++++++++
+++++++++++++++
++++++   ++++++
++++++ 2 ++++++
++++++/| ++++++
+++  / | ++++++
+++ 3--1 ++++++
+++     \++++++
+++++++++\  +++
+++++++++ 4 +++
+++++++++   +++
+++++++++++++++
+++++++++++++++
+++++++++++++++

Each cell in this grid is a three by three set of '+' signs. Four rooms are implemented with id value 1 through 4. Connections between the rooms are represented as slashes, backslashes and pipes.

The Code

class Room(object):
    def __init__(self, id, loc, exits):
        self.id = id # unique identifier, may be a name
        self.row = loc[0] # loc is tuple of (row, col)
        self.col = loc[1] 
        # exits is a list where 'X' means no exit and 
        # any other value is id of destination
        self.exits = exits 

    def __str__(self):
        directions = '\\|/- -/|\\'
        room = [ e if e == 'X' else ' ' for e in self.exits ]
        for idx in range(len(room)):
            if room[idx] == ' ':
                room[idx] = directions[idx]
            if room[idx] == 'X':
                room[idx] = ' '
        room[4] = self.id[0] # only print first char of id
        return ''.join(room)

class Map(object):
    def __init__(self, rows, cols, rooms):
        self.rows = rows
        self.cols = cols
        self.rooms = rooms

    def __str__(self):
        world = []
        for i in range(self.rows * 3):
            world.append( ['+++'] * self.cols )
        for room in self.rooms:
            ascii = str(room)
            x = room.col
            y = room.row
            for idx in range(0, 3):
                cell = ascii[idx*3:idx*3+3]
                world[y*3+idx][x] = cell
        return '\n'.join( [ ''.join(row) for row in world ] )


if __name__ == '__main__':
    # set up four rooms
    # each room has unique id (string of any length) and coordinates
    # it also has a set of 8 possible exits, represented as a list where
    # 'X' means exit is blocked and valid exits contain the id of the target room
    r1 = Room(id='1', loc=(2,2), exits=['X','2','X',
                                        '3',' ','X',
                                        'X','X','4',])
    r2 = Room(id='2', loc=(1,2), exits=['X','X','X',
                                        'X',' ','X',
                                        '3','1','X',])
    r3 = Room(id='3', loc=(2,1), exits=['X','X','2',
                                        'X',' ','1',
                                        'X','X','X',])
    r4 = Room(id='4', loc=(3,3), exits=['1','X','X',
                                        'X',' ','X',
                                        'X','X','X',])
    # initialize Map with a list of these four rooms
    map = Map(rows = 5, cols=5, rooms=[r1, r2, r3, r4])
    print map

The moving routine is not implemented, and for this representation to work, only single character ids will show up nicely.

The advantages of this system:

• easy to add rooms and to remove them
• the definition of a room is human readable
• the output functions overload __str__ and hence rooms and grid "print themselves" and this might come in useful for future debugging or adaptation to future formats e.g. as cells in an HTML table.