writing arrays to binary file

[Sheldon]

Hi everyone,

I have a short program the writes the output data to an acsii file:

import sys
import os
import string
import gisdata
from Numeric import *

def latlon(area_id, i, j):
    lon_file = "lon_%s.dat" % area_id
    flon        = open(lon_file, 'wa')
    lat_file   = "lat_%s.dat" % area_id
    flat          = open(lat_file, 'wa')
    for x in range(i):
        for y in range(j):
            flat.write("%f\n" % gisdata.xy2lonlat(area_id,x,y)[1])
            flon.write("%f\n" % gisdata.xy2lonlat(area_id,x,y)[0])
    flat.close()
    flon.close()
#------------------------------------------------------------
if __name__ == '__main__':
    tile_info ={"ibla_35n13e":[1215,1215],
                       "ibla_46n16e":[1215,1215],
                       "ibla_57n40w":[1215,1215],
                       }
    for t in tile_info.keys():
        xsize = tile_info[t][0]
        ysize = tile_info[t][1]
        result = latlon_(t, xsize, ysize)
Now this works but the output is in ascii form. Whenever I try to write
it binary form by creating the 2D array and then opening the file with
open("filename", 'wb'), I lose the decimals that are vital. The input
data is float with about 4 decimal places.
Does anyone have any ideas of how to improve this by writing the 2D
array in binary form?

Thanks,
Sheldon