117 lines
3.7 KiB
Python
117 lines
3.7 KiB
Python
"""
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First Order Exponentialy Weighted Fuzzy Time Series by Sadaei et al. (2013)
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H. J. Sadaei, R. Enayatifar, A. H. Abdullah, and A. Gani, “Short-term load forecasting using a hybrid model with a
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refined exponentially weighted fuzzy time series and an improved harmony search,” Int. J. Electr. Power Energy Syst., vol. 62, no. from 2005, pp. 118–129, 2014.
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"""
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import numpy as np
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from pyFTS.common import FuzzySet,FLR,fts, flrg
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default_c = 1.1
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class ExponentialyWeightedFLRG(flrg.FLRG):
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"""First Order Exponentialy Weighted Fuzzy Logical Relationship Group"""
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def __init__(self, LHS, **kwargs):
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super(ExponentialyWeightedFLRG, self).__init__(1, **kwargs)
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self.LHS = LHS
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self.RHS = []
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self.count = 0.0
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self.c = kwargs.get("c",default_c)
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self.w = None
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def append_rhs(self, c, **kwargs):
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count = kwargs.get('count', 1.0)
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self.RHS.append(c)
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self.count += count
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def weights(self):
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if self.w is None:
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wei = [self.c ** k for k in np.arange(0.0, self.count, 1.0)]
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tot = sum(wei)
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self.w = np.array([k / tot for k in wei])
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return self.w
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def __str__(self):
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tmp = self.LHS + " -> "
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tmp2 = ""
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cc = 0
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wei = [self.c ** k for k in np.arange(0.0, self.count, 1.0)]
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tot = sum(wei)
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for c in sorted(self.RHS):
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if len(tmp2) > 0:
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tmp2 = tmp2 + ","
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tmp2 = tmp2 + c + "(" + str(wei[cc] / tot) + ")"
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cc = cc + 1
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return tmp + tmp2
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def __len__(self):
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return len(self.RHS)
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class ExponentialyWeightedFTS(fts.FTS):
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"""First Order Exponentialy Weighted Fuzzy Time Series"""
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def __init__(self, **kwargs):
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super(ExponentialyWeightedFTS, self).__init__(order=1, name="EWFTS", **kwargs)
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self.name = "Exponentialy Weighted FTS"
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self.detail = "Sadaei"
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self.c = kwargs.get('c', default_c)
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def generate_flrg(self, flrs, c):
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for flr in flrs:
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if flr.LHS in self.flrgs:
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self.flrgs[flr.LHS].append_rhs(flr.RHS)
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else:
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self.flrgs[flr.LHS] = ExponentialyWeightedFLRG(flr.LHS, c=c);
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self.flrgs[flr.LHS].append_rhs(flr.RHS)
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def train(self, data, **kwargs):
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tmpdata = self.partitioner.fuzzyfy(data, method='maximum', mode='sets')
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flrs = FLR.generate_recurrent_flrs(tmpdata)
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self.generate_flrg(flrs, self.c)
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def forecast(self, ndata, **kwargs):
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explain = kwargs.get('explain', False)
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if self.partitioner is not None:
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ordered_sets = self.partitioner.ordered_sets
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else:
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ordered_sets = FuzzySet.set_ordered(self.partitioner.sets)
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data = np.array(ndata)
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l = len(ndata)
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ret = []
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for k in np.arange(0, l):
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actual = FuzzySet.get_maximum_membership_fuzzyset(ndata[k], self.partitioner.sets, ordered_sets)
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if explain:
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print("Fuzzyfication:\n\n {} -> {} \n".format(ndata[k], actual.name))
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if actual.name not in self.flrgs:
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ret.append(actual.centroid)
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if explain:
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print("Rules:\n\n {} -> {} (Naïve)\t Midpoint: {} \n\n".format(actual.name, actual.name,actual.centroid))
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else:
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flrg = self.flrgs[actual.name]
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mp = flrg.get_midpoints(self.partitioner.sets)
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final = mp.dot(flrg.weights())
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ret.append(final)
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if explain:
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print("Rules:\n\n {} \n\n ".format(str(flrg)))
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print("Midpoints: \n\n {}\n\n".format(mp))
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print("Deffuzyfied value: {} \n".format(final))
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return ret
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