adding pre-baked triangular and trapezoidal MF

simpful/__init__.py

@@ -1,3 +1,3 @@
 from .simpful import FuzzySystem, LinguisticVariable, UndefinedUniverseOfDiscourseError
 from .rule_parsing import Clause, Functional, OR, AND, AND_p, NOT, preparse, postparse, find_index_operator, curparse
-from .fuzzy_sets import FuzzySet, MF_object, gaussian, Sigmoid_MF, InvSigmoid_MF, Gaussian_MF, InvGaussian_MF, DoubleGaussian_MF
+from .fuzzy_sets import FuzzySet, MF_object, gaussian, Sigmoid_MF, InvSigmoid_MF, Gaussian_MF, InvGaussian_MF, DoubleGaussian_MF, Triangular_MF, Trapezoidal_MF

simpful/fuzzy_sets.py

@@ -19,6 +19,55 @@ def __call__(self, x):
 def gaussian(x, mu, sig):
     return np.exp(-np.power(x - mu, 2.) / (2 * np.power(sig, 2.)))
 
+class Triangular_MF(MF_object):
+
+	def __init__(self, a=0, b=0.5, c=1):
+		"""
+		Creates a triangular membership function.
+		Requires a <= b <= c.
+		"""
+		self._a = a
+		self._b = b
+		self._c = c
+
+	def _execute(self, x):
+		if x < self._b:
+			if self._a != self._b:
+				return (x-self._a) * (1/(self._b-self._a))
+			else:
+				return 1
+		else:
+			if self._b != self._c:
+				return 1 + (x-self._b) * (-1/(self._c-self._b))
+			else:
+				return 1
+
+class Trapezoidal_MF(MF_object):
+
+	def __init__(self, a=0, b=0.25, c=0.75, d=1):
+		"""
+		Creates a trapezoidal membership function.
+		Requires a <= b <= c <= d.
+		"""
+		self._a = a
+		self._b = b
+		self._c = c
+		self._d = d
+
+	def _execute(self, x):
+		if x < self._b:
+			if self._a != self._b:
+				return (x-self._a) * (1/(self._b-self._a))
+			else:
+				return 1
+		elif x >= self._b and x <= self._c:
+			return 1
+		else:
+			if self._c != self._d:
+				return 1 + (x-self._c) * (-1/(self._d-self._c))
+			else:
+				return 1
+
 class Sigmoid_MF(MF_object):
 
 	def __init__(self, c=0, a=1):

simpful/simpful.py

@@ -1,5 +1,5 @@
 from pylab import *
-from .fuzzy_sets import FuzzySet, MF_object, Sigmoid_MF, InvSigmoid_MF, Gaussian_MF, InvGaussian_MF, DoubleGaussian_MF
+from .fuzzy_sets import FuzzySet, MF_object, Sigmoid_MF, InvSigmoid_MF, Gaussian_MF, InvGaussian_MF, DoubleGaussian_MF, Triangular_MF, Trapezoidal_MF
 from .rule_parsing import curparse, preparse, postparse
 from numpy import array, linspace
 from scipy.interpolate import interp1d
@@ -34,7 +34,7 @@ def __init__(self, FS_list=[], concept=None, universe_of_discourse=None):
 		Args:
 			FS_list: a list of FuzzySet instances.
 			concept: a brief description of the concept represented by the linguistic variable.
-			universe_of_discourse: A list of two elements, specifying min and max of universe of discourse.
+			universe_of_discourse: a list of two elements, specifying min and max of universe of discourse.
 			It must be specified to exploit plotting facilities.
 		"""
 
@@ -371,8 +371,8 @@ def Mamdani_inference(self, terms=None, ignore_errors=False, verbose=False, subd
 		Performs Mamdani fuzzy inference.
 		Args:
 			terms: list of the names of the variables on which inference must be performed.
-			subdivisions: the number of integration steps to be performed (default: 1000).
 			If empty, all variables appearing in the consequent of a fuzzy rule are inferred.
+			subdivisions: the number of integration steps to be performed (default: 1000).
 			ignore_errors: True/False, toggles the raising of errors during the inference.
 			verbose: True/False, toggles verbose mode.