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Python

Posted by Cody Mills
Cody Mills
1,567 Points

Dungeon Game draw_map() Explanation

I have recently finished the Dungeon Game, and I was wondering if anyone would care to elaborate on the draw_map() function below. I am not quite sure I understand what is fully going on with the for loop.

def draw_map(player):
  print(' _ _ _')
  tile = '|{}'

  for idx, cell in enumerate(CELLS):
    if idx in [0, 1, 3, 4, 6, 7]:
      if cell == player:
        print(tile.format('X'), end='')
      else:
        print(tile.format('_'), end='')
    else:
      if cell == player:
        print(tile.format('X|'))
      else:
        print(tile.format('_|'))

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,468 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,468 Points

Though the "grid" is presented as 2-dimensional, the grid points are contained in a linear list. So the grid points go Left, Center, Right, Left, Center, Right, Left, Center, Right. Only the Right ones (in positions 2,5, and 8) need a trailing "|" character.

Since the tile is a trivial, formatting '|{}' to '|X' could have been a simple print.

Added comments to code. 

def draw_map(player):
  # draw top of grid
  print(' _ _ _')
  tile = '|{}'

  # process each cell (grid point)
  for idx, cell in enumerate(CELLS):
    # if cell is not a Right edge....
    if idx in [0, 1, 3, 4, 6, 7]:
      if cell == player:
        # print "|X"
        print(tile.format('X'), end='')
      else:
        # print "|_"
        print(tile.format('_'), end='')
    else:
      # cell IS Right edge
      if cell == player:
        # print "|X|" 
        print(tile.format('X|'))
      else:
        # print "|_|"
        print(tile.format('_|'))
Brandon McClelland
Brandon McClelland
4,645 Points
Brandon McClelland
Brandon McClelland
4,645 Points

Looping over the cells of a two dimensional array (think graph paper). You've got idx and cell defining the two axes of the XY plain. Only some of the cells will contain a "_". In the others, it will contain "_|". Unless the player is present, then just draw the "X" or "X| " depending on which idx the loop is iterating over.