Mercurial > repos > xuebing > sharplabtool

comparison tools/filters/randomlines.py @ 0:9071e359b9a3

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author xuebing
date Fri, 09 Mar 2012 19:37:19 -0500
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-1:000000000000 0:9071e359b9a3
1 #!/usr/bin/env python
2 # Kanwei Li, 2010
3 # Selects N random lines from a file and outputs to another file
4
5 import random, sys
6
7 def main():
8 infile = open(sys.argv[1], 'r')
9 total_lines = int(sys.argv[2])
10
11 if total_lines < 1:
12 sys.stderr.write( "Must select at least one line." )
13 sys.exit()
14
15 kept = []
16 n = 0
17 for line in infile:
18 line = line.rstrip("\n")
19 n += 1
20 if (n <= total_lines):
21 kept.append(line)
22 elif random.randint(1, n) <= total_lines:
23 kept.pop(random.randint(0, total_lines-1))
24 kept.append(line)
25
26 if n < total_lines:
27 sys.stderr.write( "Error: asked to select more lines than there were in the file." )
28 sys.exit()
29
30 open(sys.argv[3], 'w').write( "\n".join(kept) )
31
32 if __name__ == "__main__":
33 main()