pyFTS/partitioners/Huarng.py

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import numpy as np
import math
import random as rnd
import functools, operator
from pyFTS.common import FuzzySet, Membership, Transformations
# K. H. Huarng, “Effective lengths of intervals to improve forecasting in fuzzy time series,”
# Fuzzy Sets Syst., vol. 123, no. 3, pp. 387394, Nov. 2001.
from pyFTS.partitioners import partitioner
class HuarngPartitioner(partitioner.Partitioner):
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def __init__(self, data,npart,func = Membership.trimf, transformation=None):
super(HuarngPartitioner, self).__init__("Huarng", data, npart, func=func, transformation=transformation)
def build(self, data):
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diff = Transformations.Differential(1)
data2 = diff.apply(data)
davg = np.abs( np.mean(data2) / 2 )
if davg <= 1.0:
base = 0.1
elif 1 < davg <= 10:
base = 1.0
elif 10 < davg <= 100:
base = 10
else:
base = 100
sets = []
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dlen = self.max - self.min
npart = math.ceil(dlen / base)
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partition = math.ceil(self.min)
for c in range(npart):
sets.append(
FuzzySet.FuzzySet(self.prefix + str(c), Membership.trimf, [partition - base, partition, partition + base], partition))
partition += base
return sets