simple python script to convert map data from json to a binary format

binarymapconverter.py

import sys,struct,json

if len(sys.argv) != 2:
    print "No! One argument, the json map, come on"
    exit()

with open(sys.argv[1]) as f:
    map = json.load(f)
    mapdata = map['layers'][0]['data']
    for item in mapdata:
        sys.stdout.write( struct.pack('B',int(item)-1) )
    #Append column-ordered version
    width = map['layers'][0]['width']
    height = map['layers'][0]['height']
    for col in range(width):
        for row in range(height):
            item = mapdata[col + row*width]
            sys.stdout.write( struct.pack('B',int(item)-1) )