pyFTS/partitioners/Huarng.py
2016-12-26 15:47:23 -02:00

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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.
def GridPartitionerTrimf(data, prefix="A"):
data2 = Transformations.differential(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 = []
dmax = max(data)
dmax += dmax * 0.10
dmin = min(data)
dmin -= dmin * 0.10
dlen = dmax - dmin
npart = math.ceil(dlen / base)
partition = math.ceil(dmin)
for c in range(npart):
sets.append(
FuzzySet.FuzzySet(prefix + str(c), Membership.trimf, [partition - base, partition, partition + base], partition))
partition += base
return sets