Writing ASCII grid files

This is a quick demo on how to create ASCII grid files  of a variety of forms using Python's random module. 

'''
write_ascii.py
A quick demo on creating an ascii grid which can be used for testing
purposes.  Everything is hard coded now, but it could easily be
converted to a tool for use in programs.  You can create random
integer, uniform etc grids using the python random options.
Specify the filename, classes etc below
can also use:
  randint( a, b) random integer between a and b
  uniform( a, b) random float between a and b
  betavariate( alpha, beta)
  gammavariate( alpha, beta)
  gauss( mu, sigma)
  lognormvariate( mu, sigma)
  amongst others, check the Python random module documentation
'''
import random
output_file = "c:/temp/Ascii_nodata.asc"   #alter to suit
classes = 4
ncols = 10
nrows = 10
xllcorner =    0
yllcorner =    0
cellsize  =    1
NODATA_value =  -9999
header = ["ncols          " + str(ncols) + "\n",
         "nrows          " + str(nrows) + "\n",
         "xllcorner      " + str(xllcorner) + "\n",
         "yllcorner      " + str(yllcorner) + "\n",
         "cellsize       " + str(cellsize) + "\n",
         "NODATA_value   " + str(NODATA_value)]
out_file = open(output_file,'w')
for i in header:
  out_file.write(i)
for i in range(nrows):
  a_line = "\n"
  for j in range(ncols):
    a_val = int(random.random() * classes)  #integer value
    #a_val = random.randint(0, 4)            #random integer in range 0-4
    a_line += str(a_val) + " "
  out_file.write(a_line)
out_file.close()