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Core Python Programming Exercises P09-20

9-20.

Compressed Files. Write a short piece of code that will compress and decompress gzipped or bzipped files. Confirm your solution works by using the command-line gzip or bzip2 programs or a GUI program like PowerArchiver, StuffIt, and/or WinZip.

#!/usr/bin/env python
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#-*- coding:utf-8 -*-
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#$Id: p0920.py 166 2010-06-29 03:46:56Z xylz $
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'''
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This is a 'python' study plan for xylz.
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'''
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import gzip
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import os
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def compress (dst,f):
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print "compress %s to %s" % (f,dst)
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f_out = gzip.open(dst,'wb')
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f_in = open(f,'rb')
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f_out.writelines(f_in)
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f_in.close()
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f_out.close()
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in_size = os.path.getsize(f)
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out_size = os.path.getsize(dst)
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print "source size %d bytes, target size %d bytes, %d%%" % (in_size,out_size,(out_size*100/in_size))
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def decompress (f,dst):
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print "decompress %s to %s" % (f,dst)
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f_in = gzip.open(f,'rb')
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f_out = open(dst,'wb')
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f_out.writelines(f_in)
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f_in.close()
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f_out.close()
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in_size = os.path.getsize(f)
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out_size = os.path.getsize(dst)
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print "source size %d bytes, target size %d bytes, %d%%" % (in_size,out_size,(in_size*100/out_size))
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if __name__ == '__main__':
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import sys
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if len(sys.argv)<3 or ('c'!= sys.argv[1] and 'x'!= sys.argv[1]):
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print "Usage: %s <c|x> <file> [destfile]" % (sys.argv[0],)
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sys.exit(0)
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src_file = sys.argv[2]
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dest_file = None
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if len(sys.argv)>3:
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dest_file = sys.argv[3]
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if 'c' == sys.argv[1]:
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if not dest_file:
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dest_file = src_file+".gz"
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compress(dest_file,src_file)
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else:
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if not dest_file:
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dest_file = src_file[:src_file.index('.gz')] #raise exception if file error
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decompress(src_file,dest_file)
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下面是一次執行的輸出結果：

C:\Users\xylz\Desktop\core_python>python p0920.py

Usage: p0920.py <c|x> <file> [destfile]

C:\Users\xylz\Desktop\core_python>python p0920.py c p0920.py

compress p0920.py to p0920.py.gz

source size 1587 bytes, target size 614 bytes, 38%

C:\Users\xylz\Desktop\core_python>python p0920.py x p0920.py.gz p0920.py.2

decompress p0920.py.gz to p0920.py.2

source size 614 bytes, target size 1587 bytes, 38%

C:\Users\xylz\Desktop\core_python>md5sum p0920.py p0920.py.2

3383e1a05fbede400dd016feed8a55bf *p0920.py

3383e1a05fbede400dd016feed8a55bf *p0920.py.2

posted on 2010-06-29 11:51 imxylz 閱讀(16701) 評論(0) 編輯收藏所屬分類: Python

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