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Source Code for Module fuzzy.defuzzify.MaxLeft

 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  """Defuzzification which uses the left global maximum.""" 
20   
21  __revision__ = "$Id: MaxLeft.py,v 1.8 2010-03-28 18:40:33 rliebscher Exp $" 
22   
23  from fuzzy.defuzzify.Base import Base, DefuzzificationException 
24   
25 -class MaxLeft(Base): 
26      """Defuzzification which uses the left global maximum.""" 
27   
28 -    def __init__(self, INF=None, ACC=None, failsafe=None, *args, **keywords): 
29          """Initialize the defuzzification method with INF,ACC  
30          and an optional value in case defuzzification is not possible""" 
31          super(MaxLeft, self).__init__(INF, ACC, *args, **keywords) 
32          self.failsafe = failsafe # which value if value not calculable 
33   
34 -    def getValue(self, variable): 
35          """Defuzzification.""" 
36          try: 
37              temp = self.accumulate(variable) 
38   
39              # get polygon representation 
40              table = list(self.value_table(temp)) 
41   
42              if len(table) == 0: 
43                  raise DefuzzificationException("no value calculable: complete undefined set") 
44   
45              y = table[0][1] 
46              x = float('-inf') # left end of polygon is always -infinity 
47   
48              for (x_, y_) in table[1:]: 
49                  if y_ > y: 
50                      y = y_ 
51                      x = x_ 
52   
53              return x 
54          except: 
55              # was not to calculate 
56              if self.failsafe is not None: 
57                  # user gave us a value to return 
58                  return self.failsafe 
59              else: 
60                  raise 
61   
62 -    def _repr_params(self, params): 
63          """Helper for representation of instance. 
64           
65          Add all own params to given list in params.     
66          """ 
67          super(MaxLeft, self)._repr_params(params) 
68          if self.failsafe: params.append("failsafe=%s" % self.failsafe) 
69   

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