75 lines
2.0 KiB
Python
75 lines
2.0 KiB
Python
"""
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Membership functions for Fuzzy Sets
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"""
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import numpy as np
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import math
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from pyFTS import *
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def trimf(x, parameters):
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"""
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Triangular fuzzy membership function
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:param x: data point
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:param parameters: a list with 3 real values
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:return: the membership value of x given the parameters
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"""
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xx = np.round(x, 3)
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if xx < parameters[0]:
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return 0
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elif parameters[0] <= xx < parameters[1]:
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return (x - parameters[0]) / (parameters[1] - parameters[0])
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elif parameters[1] <= xx <= parameters[2]:
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return (parameters[2] - xx) / (parameters[2] - parameters[1])
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else:
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return 0
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def trapmf(x, parameters):
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"""
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Trapezoidal fuzzy membership function
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:param x: data point
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:param parameters: a list with 4 real values
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:return: the membership value of x given the parameters
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"""
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if x < parameters[0]:
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return 0
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elif parameters[0] <= x < parameters[1]:
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return (x - parameters[0]) / (parameters[1] - parameters[0])
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elif parameters[1] <= x <= parameters[2]:
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return 1
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elif parameters[2] <= x <= parameters[3]:
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return (parameters[3] - x) / (parameters[3] - parameters[2])
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else:
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return 0
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def gaussmf(x, parameters):
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"""
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Gaussian fuzzy membership function
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:param x: data point
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:param parameters: a list with 2 real values (mean and variance)
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:return: the membership value of x given the parameters
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"""
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return math.exp((-(x - parameters[0])**2)/(2 * parameters[1]**2))
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def bellmf(x, parameters):
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"""
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Bell shaped membership function
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:param x:
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:param parameters:
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:return:
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"""
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return 1 / (1 + abs((x - parameters[2]) / parameters[0]) ** (2 * parameters[1]))
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def sigmf(x, parameters):
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"""
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Sigmoid / Logistic membership function
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:param x:
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:param parameters: an list with 2 real values (smoothness and midpoint)
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:return:
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"""
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return 1 / (1 + math.exp(-parameters[0] * (x - parameters[1])))
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