#!/usr/bin/env python | |
# Takes an optional filename, defaulting to this file itself. | |
# Reads the file and compresses the content using level 1 and level 9 | |
# compression, printing a summary of the results. | |
import zlib, sys | |
def main(): | |
if len(sys.argv) > 1: | |
filename = sys.argv[1] | |
else: | |
filename = sys.argv[0] | |
print 'Reading', filename | |
f = open(filename, 'rb') # Get the data to compress | |
s = f.read() | |
f.close() | |
# First, we'll compress the string in one step | |
comptext = zlib.compress(s, 1) | |
decomp = zlib.decompress(comptext) | |
print '1-step compression: (level 1)' | |
print ' Original:', len(s), 'Compressed:', len(comptext), | |
print 'Uncompressed:', len(decomp) | |
# Now, let's compress the string in stages; set chunk to work in smaller steps | |
chunk = 256 | |
compressor = zlib.compressobj(9) | |
decompressor = zlib.decompressobj() | |
comptext = decomp = '' | |
for i in range(0, len(s), chunk): | |
comptext = comptext+compressor.compress(s[i:i+chunk]) | |
# Don't forget to call flush()!! | |
comptext = comptext + compressor.flush() | |
for i in range(0, len(comptext), chunk): | |
decomp = decomp + decompressor.decompress(comptext[i:i+chunk]) | |
decomp=decomp+decompressor.flush() | |
print 'Progressive compression (level 9):' | |
print ' Original:', len(s), 'Compressed:', len(comptext), | |
print 'Uncompressed:', len(decomp) | |
if __name__ == '__main__': | |
main() |