compute_something.py

#!/usr/bin/python

#Write tool to compute GC contect here
# usage : python compute_comething.py <FASTA file> <output file>

import re,sys
import string
 
inp = sys.argv[1]
out = sys.argv[2]

file = open(inp,"r")
gcCount = 0
totalBaseCount = 0
for line in file:
    line = line.strip("\n")
    if not line.startswith(">"):
        gcCount += len(re.findall("[GC]", line))
        totalBaseCount += len(re.findall("[GCTA]", line))
gcFraction = float(gcCount) / totalBaseCount
print( gcFraction * 100 )

out = open(out,"w")
out.write(str(gcFraction*100))
out.close()