[Tutor] Comparing files, Counting Value

Michiyo LaBerge mlaberge at labergedaylight.com
Tue Feb 1 00:27:24 CET 2005

```Hello all,

I'm very new to Python and have been trying to write a script to
compare data from 2 files and getting a total. One of the two files
contains x, y positions of pixels and a color value(z) of each, so it
has three columns in the file. The other file has two columns; x1, y1.
I'd like to get only x, y positions which match to x1, y1 of the second
file and then look up the z value. If the z value is greater than a
certain number, it counts 1, otherwise it moves on the next x, y
position. Finally, I'm able to get total count of the pixels that are
over the threshold. The script I'm using is below step by step,
however, I haven't been able to figure out the error massage
"IndexError: list index out of range" on z value. Any comments would be
appreciated!

Regards,
Michiyo

file 1:								file 2:
299     189       8.543e-02					260	168
300     189       0.000e+00					270	180
301     189       0.000e+00					299	189
302     189       0.000e+00					300	170
0        188       5.095e-02					301	189
1        188       5.108e-02					  .	   .
.		.		.						  .         .
.		.		.						  .	   .

#!usr/local/bin/python

import sys

i=open("file 1") #value data
o=open("file 2") #look-up file
l=open("result", 'w')#result

results={}

while line:
fields=line.split()
x1=fields[0, 1] in i    #x,y position in file 1
z=fields[2] in i           #value data in file 1
x2=fields[0, 1] in o   #x,y position in file 2

if x1 == x2:

if z >= 5.000e-02:
z=1
count(n=0)
print>>l, count(1)

i.close()
o.close()
l.close()

```