rdkit.DataStructs.LazySignature

Package rdkit :: Package DataStructs :: Module LazySignature |
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# Source Code for Module rdkit.DataStructs.LazySignature

     1  # $Id$
     2  #
     3  #  Copyright (C) 2005 Rational Discovery LLC
     4  #   All Rights Reserved
     5  #
     6
     7
     8 -class LazySig:
     9 -  def __init__(self,computeFunc,sigSize):
    10      """
    11      computeFunc should take a single argument, the integer bit id
    12      to compute
    13
    14      """
    15      if sigSize<=0:
    16        raise ValueError('zero size')
    17      self.computeFunc=computeFunc
    18      self.size=sigSize
    19      self._cache={}
    20
    21 -  def __len__(self):
    22      """
    23
    24       >>> obj = LazySig(lambda x:1,10)
    25       >>> len(obj)
    26       10
    27
    28      """
    29      return self.size
    30
    31 -  def __getitem__(self,which):
    32      """
    33
    34       >>> obj = LazySig(lambda x:x,10)
    35       >>> obj[1]
    36       1
    37       >>> obj[-1]
    38       9
    39       >>> try:
    40       ...   obj[10]
    41       ... except IndexError:
    42       ...   1
    43       ... else:
    44       ...   0
    45       1
    46       >>> try:
    47       ...   obj[-10]
    48       ... except IndexError:
    49       ...   1
    50       ... else:
    51       ...   0
    52       1
    53
    54      """
    55      if which<0:
    56        # handle negative indices
    57        which = self.size+which
    58
    59      if which<=0 or which>=self.size:
    60        raise IndexError('bad index')
    61
    62      if which in self._cache:
    63        v= self._cache[which]
    64      else:
    65        v = self.computeFunc(which)
    66        self._cache[which]=v
    67      return v
    68
    69  #------------------------------------
    70  #
    71  #  doctest boilerplate
    72  #
    73 -def _test():
    74    import doctest,sys
    75    return doctest.testmod(sys.modules["__main__"])
    76
    77
    78  if __name__ == '__main__':
    79    import sys
    80    failed,tried = _test()
    81    sys.exit(failed)
    82