Benjamin Peterson | 90f5ba5 | 2010-03-11 22:53:45 +0000 | [diff] [blame] | 1 | #!/usr/bin/env python3 |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 2 | |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 3 | # Takes an optional filename, defaulting to this file itself. |
| 4 | # Reads the file and compresses the content using level 1 and level 9 |
| 5 | # compression, printing a summary of the results. |
| 6 | |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 7 | import zlib, sys |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 8 | |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 9 | def main(): |
| 10 | if len(sys.argv) > 1: |
| 11 | filename = sys.argv[1] |
| 12 | else: |
| 13 | filename = sys.argv[0] |
Collin Winter | 6f2df4d | 2007-07-17 20:59:35 +0000 | [diff] [blame] | 14 | print('Reading', filename) |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 15 | |
Georg Brandl | 2db2b8a | 2010-08-02 23:15:58 +0000 | [diff] [blame] | 16 | with open(filename, 'rb') as f: # Get the data to compress |
| 17 | s = f.read() |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 18 | |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 19 | # First, we'll compress the string in one step |
| 20 | comptext = zlib.compress(s, 1) |
| 21 | decomp = zlib.decompress(comptext) |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 22 | |
Collin Winter | 6f2df4d | 2007-07-17 20:59:35 +0000 | [diff] [blame] | 23 | print('1-step compression: (level 1)') |
| 24 | print(' Original:', len(s), 'Compressed:', len(comptext), end=' ') |
| 25 | print('Uncompressed:', len(decomp)) |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 26 | |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 27 | # Now, let's compress the string in stages; set chunk to work in smaller steps |
Guido van Rossum | 5416a0d | 1997-05-28 16:13:21 +0000 | [diff] [blame] | 28 | |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 29 | chunk = 256 |
| 30 | compressor = zlib.compressobj(9) |
| 31 | decompressor = zlib.decompressobj() |
Georg Brandl | 2db2b8a | 2010-08-02 23:15:58 +0000 | [diff] [blame] | 32 | comptext = decomp = b'' |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 33 | for i in range(0, len(s), chunk): |
Georg Brandl | 2db2b8a | 2010-08-02 23:15:58 +0000 | [diff] [blame] | 34 | comptext += compressor.compress(s[i:i+chunk]) |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 35 | # Don't forget to call flush()!! |
Georg Brandl | 2db2b8a | 2010-08-02 23:15:58 +0000 | [diff] [blame] | 36 | comptext += compressor.flush() |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 37 | |
| 38 | for i in range(0, len(comptext), chunk): |
Georg Brandl | 2db2b8a | 2010-08-02 23:15:58 +0000 | [diff] [blame] | 39 | decomp += decompressor.decompress(comptext[i:i+chunk]) |
| 40 | decomp += decompressor.flush() |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 41 | |
Collin Winter | 6f2df4d | 2007-07-17 20:59:35 +0000 | [diff] [blame] | 42 | print('Progressive compression (level 9):') |
| 43 | print(' Original:', len(s), 'Compressed:', len(comptext), end=' ') |
| 44 | print('Uncompressed:', len(decomp)) |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 45 | |
| 46 | if __name__ == '__main__': |
| 47 | main() |