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Source Code for Module fuzzy.set.ZFunction

 1  # -*- coding: utf-8 -*- 
 2  # 
 3  # Copyright (C) 2009  Rene Liebscher 
 4  # 
 5  # This program is free software; you can redistribute it and/or modify it under 
 6  # the terms of the GNU Lesser General Public License as published by the Free  
 7  # Software Foundation; either version 3 of the License, or (at your option) any 
 8  # later version. 
 9  # 
10  # This program is distributed in the hope that it will be useful, but WITHOUT  
11  # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 
12  # FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more 
13  # details. 
14  #  
15  # You should have received a copy of the GNU Lesser General Public License 
16  # along with this program; if not, see <http://www.gnu.org/licenses/>.  
17  # 
18   
19  """Realize a Z-shaped fuzzy set.""" 
20   
21  __revision__ = "$Id: ZFunction.py,v 1.17 2010-03-28 18:44:46 rliebscher Exp $" 
22   
23   
24  from fuzzy.set.SFunction import SFunction 
25   
26 -class ZFunction(SFunction): 
27      r"""Realize a Z-shaped fuzzy set:: 
28             __ 
29               \ 
30               |\ 
31               | \ 
32               | |\ 
33               | | \__ 
34               | a | 
35               |   | 
36              2*delta 
37   
38      see also U{http://pyfuzzy.sourceforge.net/demo/set/ZFunction.png} 
39       
40      @ivar a: center of set. 
41      @type a: float 
42      @ivar delta: absolute distance between x-values for minimum and maximum. 
43      @type delta: float 
44      """ 
45   
46 -    def __init__(self, a=0.0, delta=1.0): 
47          """Initialize a Z-shaped fuzzy set. 
48   
49          @param a: center of set 
50          @type a: float 
51          @param delta: absolute distance between x-values for minimum and maximum 
52          @type delta: float 
53          """ 
54          super(ZFunction, self).__init__(a, delta) 
55   
56   
57 -    def __call__(self, x): 
58          """Return membership of x in this fuzzy set. 
59             This method makes the set work like a function. 
60              
61             @param x: value for which the membership is to calculate 
62             @type x: float 
63             @return: membership 
64             @rtype: float 
65             """ 
66          return 1.0 - SFunction.__call__(self, x) 
67   

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