Demo/zlib/zlibdemo.py

   1 #!/usr/bin/env python
   2
   3 import zlib, sys
   4 if len(sys.argv)>1: filename=sys.argv[1]
   5 else: filename='zlibdemo.py'
   6 print 'Reading', filename
   7 f=open(filename, 'r')           # Get the data to compress
   8 s=f.read()
   9 f.close()
  10
  11 # First, we'll compress the string in one step
  12 comptext=zlib.compress(s, 1)
  13 decomp=zlib.decompress(comptext)
  14
  15 print '1-step compression: (level 1)'
  16 print '    Original:', len(s), 'Compressed:', len(comptext),
  17 print 'Uncompressed:', len(decomp)
  18
  19 # Now, let's compress the string in stages; set chunk to work in smaller steps
  20
  21 chunk=256
  22 compressor=zlib.compressobj(9)
  23 decompressor=zlib.decompressobj()
  24 comptext=decomp=''
  25 for i in range(0, len(s), chunk):
  26     comptext=comptext+compressor.compress(s[i:i+chunk])
  27 comptext=comptext+compressor.flush()    # Don't forget to call flush()!!
  28
  29 for i in range(0, len(comptext), chunk):
  30     decomp=decomp+decompressor.decompress(comptext[i:i+chunk])
  31 decomp=decomp+decompressor.flush()
  32
  33 print 'Progressive compression (level 9):'
  34 print '    Original:', len(s), 'Compressed:', len(comptext),
  35 print 'Uncompressed:', len(decomp)
  36