Source Code for Module Bio.HotRand

 1  # Copyright 2002 by Katharine Lindner.  All rights reserved. 
 2  # This code is part of the Biopython distribution and governed by its 
 3  # license.  Please see the LICENSE file that should have been included 
 4  # as part of this package. 
 5   
 6  """handles true random numbers supplied from the web server of 
 7     fourmilab. Based on atmospheric noise.  The motivation is to 
 8     support biosimulations that rely on random numbers. 
 9  """ 
10   
11  import urllib 
12  from Bio import BiopythonDeprecationWarning 
13  import warnings 
14  warnings.warn("The HotRand module is deprecated and likely to be removed in a future release of Biopython. Please use an alternative RNG.", BiopythonDeprecationWarning) 
15   
16   
17 -def byte_concat( text ): 
18      val = 0 
19      numbytes = len( text ) 
20      for i in range( 0, numbytes ): 
21          val = val * 256 
22          val = val + ord( text[ i ] ) 
23   
24      return val 
25   
26   
27 -class HotCache(object): 
28   
29 -    def __init__( self  ): 
30  #        self.url = 'http://www.fourmilab.ch/cgi-bin/uncgi/Hotbits?num=5000&min=1&max=6&col=1' 
31          self.url = 'http://www.random.org/cgi-bin/randbyte?' 
32          self.query = { 'nbytes': 128, 'fmt': 'h' } 
33          self.fill_hot_cache() 
34   
35 -    def fill_hot_cache( self ): 
36          url = self.url + urllib.urlencode( self.query ) 
37          fh = urllib.urlopen( url ) 
38          self.hot_cache = fh.read() 
39          fh.close() 
40   
41 -    def next_num( self, num_digits = 4 ): 
42          cache = self.hot_cache 
43          numbytes = num_digits / 2 
44          if( len( cache ) % numbytes != 0 ): 
45              print 'len_cache is %d' % len( cache ) 
46              raise ValueError 
47          if( cache == '' ): 
48              self.fill_hot_cache() 
49              cache = self.hot_cache 
50          hexdigits = cache[ :numbytes ] 
51          self.hot_cache = cache[ numbytes: ] 
52          return byte_concat( hexdigits ) 
53   
54   
55 -class HotRandom(object): 
56   
57 -    def __init__( self ): 
58          self.hot_cache = HotCache( ) 
59   
60 -    def hot_rand( self, high, low = 0 ): 
61          span = high - low 
62          val = self.hot_cache.next_num() 
63          val = ( span * val ) >> 16 
64          val = val + low 
65          return val 
66   
67   
68  if( __name__ == '__main__' ): 
69      hot_random = HotRandom() 
70      for j in range( 0, 130 ): 
71          print hot_random.hot_rand( 25 ) 
72      nums = [ '0000', 'abcd', '1234', '5555', '4321', 'aaaa', 'ffff' ] 
73      for num in nums: 
74          print hex_convert( num ) 
75