added DMx and DMy, with a classmethod that returns HDx and HDy respectively
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@ -6,7 +6,7 @@ from tqdm import tqdm
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import quapy as qp
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from quapy.protocol import APP
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from quapy.method.aggregative import HDy
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from quapy.method.non_aggregative import HDx
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from quapy.method.non_aggregative import DMx
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"""
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@ -42,7 +42,7 @@ for dataset_name in tqdm(qp.datasets.UCI_DATASETS, total=len(qp.datasets.UCI_DAT
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# HDx............................................
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tinit = time()
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hdx = HDx().fit(train)
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hdx = DMx.HDx(n_jobs=-1).fit(train)
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t_hdx_train = time() - tinit
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tinit = time()
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@ -12,7 +12,7 @@ quantifiers = [
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('ACC', qp.method.aggregative.ACC(newLR())),
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('PCC', qp.method.aggregative.PCC(newLR())),
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('PACC', qp.method.aggregative.PACC(newLR())),
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('HDy', qp.method.aggregative.DistributionMatching(newLR())),
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('HDy', qp.method.aggregative.DMy(newLR())),
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('EMQ', qp.method.aggregative.EMQ(newLR()))
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]
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@ -1,6 +1,6 @@
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import quapy as qp
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from quapy.protocol import APP
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from quapy.method.aggregative import DistributionMatching
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from quapy.method.aggregative import DMy
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from sklearn.linear_model import LogisticRegression
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import numpy as np
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@ -8,7 +8,7 @@ import numpy as np
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In this example, we show how to perform model selection on a DistributionMatching quantifier.
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"""
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model = DistributionMatching(LogisticRegression())
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model = DMy(LogisticRegression())
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qp.environ['SAMPLE_SIZE'] = 100
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qp.environ['N_JOBS'] = -1
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@ -291,3 +291,57 @@ def get_divergence(divergence: Union[str, Callable]):
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return divergence
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else:
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raise ValueError(f'argument "divergence" not understood; use a str or a callable function')
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def argmin_prevalence(loss, n_classes, method='optim_minimize'):
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if method == 'optim_minimize':
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return optim_minimize(loss, n_classes)
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elif method == 'linear_search':
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return linear_search(loss, n_classes)
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elif method == 'ternary_search':
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raise NotImplementedError()
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else:
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raise NotImplementedError()
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def optim_minimize(loss, n_classes):
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"""
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Searches for the optimal prevalence values, i.e., an `n_classes`-dimensional vector of the (`n_classes`-1)-simplex
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that yields the smallest lost. This optimization is carried out by means of a constrained search using scipy's
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SLSQP routine.
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:param loss: (callable) the function to minimize
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:param n_classes: (int) the number of classes, i.e., the dimensionality of the prevalence vector
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:return: (ndarray) the best prevalence vector found
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"""
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from scipy import optimize
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# the initial point is set as the uniform distribution
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uniform_distribution = np.full(fill_value=1 / n_classes, shape=(n_classes,))
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# solutions are bounded to those contained in the unit-simplex
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bounds = tuple((0, 1) for _ in range(n_classes)) # values in [0,1]
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constraints = ({'type': 'eq', 'fun': lambda x: 1 - sum(x)}) # values summing up to 1
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r = optimize.minimize(loss, x0=uniform_distribution, method='SLSQP', bounds=bounds, constraints=constraints)
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return r.x
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def linear_search(loss, n_classes):
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"""
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Performs a linear search for the best prevalence value in binary problems. The search is carried out by exploring
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the range [0,1] stepping by 0.01. This search is inefficient, and is added only for completeness (some of the
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early methods in quantification literature used it, e.g., HDy). A most powerful alternative is `optim_minimize`.
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:param loss: (callable) the function to minimize
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:param n_classes: (int) the number of classes, i.e., the dimensionality of the prevalence vector
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:return: (ndarray) the best prevalence vector found
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"""
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assert n_classes==2, 'linear search is only available for binary problems'
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prev_selected, min_score = None, None
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for prev in prevalence_linspace(n_prevalences=100, repeats=1, smooth_limits_epsilon=0.0):
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score = loss(np.asarray([1 - prev, prev]))
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if min_score is None or score < min_score:
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prev_selected, min_score = prev, score
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return np.asarray([1 - prev_selected, prev_selected])
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@ -568,10 +568,11 @@ class HDy(AggregativeProbabilisticQuantifier, BinaryQuantifier):
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self.Pxy0 = Px[validation.labels == self.classifier.classes_[0]]
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# pre-compute the histogram for positive and negative examples
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self.bins = np.linspace(10, 110, 11, dtype=int) # [10, 20, 30, ..., 100, 110]
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self.Pxy1_density = {bins: np.histogram(self.Pxy1, bins=bins, range=(0, 1), density=True)[0] for bins in
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self.bins}
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self.Pxy0_density = {bins: np.histogram(self.Pxy0, bins=bins, range=(0, 1), density=True)[0] for bins in
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self.bins}
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def hist(P, bins):
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h = np.histogram(P, bins=bins, range=(0, 1), density=True)[0]
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return h / h.sum()
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self.Pxy1_density = {bins: hist(self.Pxy1, bins) for bins in self.bins}
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self.Pxy0_density = {bins: hist(self.Pxy0, bins) for bins in self.bins}
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return self
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def aggregate(self, classif_posteriors):
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@ -712,7 +713,7 @@ class SMM(AggregativeProbabilisticQuantifier, BinaryQuantifier):
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return np.asarray([1 - class1_prev, class1_prev])
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class DistributionMatching(AggregativeProbabilisticQuantifier):
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class DMy(AggregativeProbabilisticQuantifier):
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"""
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Generic Distribution Matching quantifier for binary or multiclass quantification based on the space of posterior
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probabilities. This implementation takes the number of bins, the divergence, and the possibility to work on CDF
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@ -733,14 +734,24 @@ class DistributionMatching(AggregativeProbabilisticQuantifier):
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:param n_jobs: number of parallel workers (default None)
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"""
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def __init__(self, classifier, val_split=0.4, nbins=8, divergence: Union[str, Callable]='HD', cdf=False, n_jobs=None):
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def __init__(self, classifier, val_split=0.4, nbins=8, divergence: Union[str, Callable]='HD',
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cdf=False, search='optim_minimize', n_jobs=None):
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self.classifier = classifier
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self.val_split = val_split
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self.nbins = nbins
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self.divergence = divergence
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self.cdf = cdf
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self.search = search
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self.n_jobs = n_jobs
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@classmethod
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def HDy(cls, classifier, val_split=0.4, n_jobs=None):
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from quapy.method.meta import MedianEstimator
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hdy = DMy(classifier=classifier, val_split=val_split, search='linear_search', divergence='HD')
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hdy = MedianEstimator(hdy, param_grid={'nbins': np.linspace(10, 110, 11).astype(int)}, n_jobs=n_jobs)
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return hdy
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def __get_distributions(self, posteriors):
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histograms = []
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post_dims = posteriors.shape[1]
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@ -794,26 +805,20 @@ class DistributionMatching(AggregativeProbabilisticQuantifier):
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`n` channels (proper distributions of binned posterior probabilities), on which the divergence is computed
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independently. The matching is computed as an average of the divergence across all channels.
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:param instances: instances in the sample
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:param posteriors: posterior probabilities of the instances in the sample
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:return: a vector of class prevalence estimates
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"""
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test_distribution = self.__get_distributions(posteriors)
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divergence = get_divergence(self.divergence)
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n_classes, n_channels, nbins = self.validation_distribution.shape
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def match(prev):
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def loss(prev):
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prev = np.expand_dims(prev, axis=0)
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mixture_distribution = (prev @ self.validation_distribution.reshape(n_classes,-1)).reshape(n_channels, -1)
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divs = [divergence(test_distribution[ch], mixture_distribution[ch]) for ch in range(n_channels)]
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return np.mean(divs)
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# the initial point is set as the uniform distribution
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uniform_distribution = np.full(fill_value=1 / n_classes, shape=(n_classes,))
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return F.argmin_prevalence(loss, n_classes, method=self.search)
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# solutions are bounded to those contained in the unit-simplex
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bounds = tuple((0, 1) for x in range(n_classes)) # values in [0,1]
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constraints = ({'type': 'eq', 'fun': lambda x: 1 - sum(x)}) # values summing up to 1
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r = optimize.minimize(match, x0=uniform_distribution, method='SLSQP', bounds=bounds, constraints=constraints)
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return r.x
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def newELM(svmperf_base=None, loss='01', C=1):
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@ -1215,17 +1220,6 @@ class MS2(MS):
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return np.median(tprs), np.median(fprs)
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ClassifyAndCount = CC
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AdjustedClassifyAndCount = ACC
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ProbabilisticClassifyAndCount = PCC
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ProbabilisticAdjustedClassifyAndCount = PACC
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ExpectationMaximizationQuantifier = EMQ
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SLD = EMQ
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HellingerDistanceY = HDy
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MedianSweep = MS
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MedianSweep2 = MS2
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class OneVsAllAggregative(OneVsAllGeneric, AggregativeQuantifier):
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"""
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Allows any binary quantifier to perform quantification on single-label datasets.
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@ -1283,3 +1277,18 @@ class OneVsAllAggregative(OneVsAllGeneric, AggregativeQuantifier):
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# the estimation for the positive class prevalence
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return self.dict_binary_quantifiers[c].aggregate(classif_predictions[:, c])[1]
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#---------------------------------------------------------------
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# aliases
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#---------------------------------------------------------------
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ClassifyAndCount = CC
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AdjustedClassifyAndCount = ACC
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ProbabilisticClassifyAndCount = PCC
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ProbabilisticAdjustedClassifyAndCount = PACC
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ExpectationMaximizationQuantifier = EMQ
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DistributionMatchingY = DMy
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SLD = EMQ
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HellingerDistanceY = HDy
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MedianSweep = MS
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MedianSweep2 = MS2
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@ -1,7 +1,5 @@
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from typing import Union, Callable
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import numpy as np
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from scipy import optimize
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from functional import get_divergence
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from quapy.data import LabelledCollection
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@ -41,81 +39,7 @@ class MaximumLikelihoodPrevalenceEstimation(BaseQuantifier):
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return self.estimated_prevalence
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class HDx(BinaryQuantifier):
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"""
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`Hellinger Distance x <https://www.sciencedirect.com/science/article/pii/S0020025512004069>`_ (HDx).
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HDx is a method for training binary quantifiers, that models quantification as the problem of
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minimizing the average divergence (in terms of the Hellinger Distance) across the feature-specific normalized
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histograms of two representations, one for the unlabelled examples, and another generated from the training
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examples as a mixture model of the class-specific representations. The parameters of the mixture thus represent
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the estimates of the class prevalence values. The method computes all matchings for nbins in [10, 20, ..., 110]
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and reports the mean of the median. The best prevalence is searched via linear search, from 0 to 1 steppy by 0.01.
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"""
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def __init__(self):
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self.feat_ranges = None
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def covariate_histograms(self, X, nbins):
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assert self.feat_ranges is not None, 'quantify called before fit'
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histograms = []
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for col_idx in range(self.nfeats):
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feature = X[:,col_idx]
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feat_range = self.feat_ranges[col_idx]
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histograms.append(np.histogram(feature, bins=nbins, range=feat_range, density=True)[0])
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return np.vstack(histograms).T
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def fit(self, data: LabelledCollection):
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"""
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Trains a HDx quantifier.
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:param data: the training set
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:return: self
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"""
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self._check_binary(data, self.__class__.__name__)
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X, y = data.Xy
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self.nfeats = X.shape[1]
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self.feat_ranges = _get_features_range(X)
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# pre-compute the representation for positive and negative examples
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self.bins = np.linspace(10, 110, 11, dtype=int) # [10, 20, 30, ..., 100, 110]
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self.H0 = {bins:self.covariate_histograms(X[y == 0], bins) for bins in self.bins}
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self.H1 = {bins:self.covariate_histograms(X[y == 1], bins) for bins in self.bins}
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return self
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def quantify(self, X):
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# "In this work, the number of bins b used in HDx and HDy was chosen from 10 to 110 in steps of 10,
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# and the final estimated a priori probability was taken as the median of these 11 estimates."
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# (González-Castro, et al., 2013).
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assert X.shape[1] == self.nfeats, f'wrong shape in quantify; expected {self.nfeats}, found {X.shape[1]}'
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prev_estimations = []
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for nbins in self.bins:
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Ht = self.covariate_histograms(X, nbins=nbins)
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H0 = self.H0[nbins]
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H1 = self.H1[nbins]
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# the authors proposed to search for the prevalence yielding the best matching as a linear search
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# at small steps (modern implementations resort to an optimization procedure)
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prev_selected, min_dist = None, None
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for prev in F.prevalence_linspace(n_prevalences=100, repeats=1, smooth_limits_epsilon=0.0):
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Hx = prev * H1 + (1 - prev) * H0
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hdx = np.mean([F.HellingerDistance(Hx[:,col], Ht[:,col]) for col in range(self.nfeats)])
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if prev_selected is None or hdx < min_dist:
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prev_selected, min_dist = prev, hdx
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prev_estimations.append(prev_selected)
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class1_prev = np.median(prev_estimations)
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return np.asarray([1 - class1_prev, class1_prev])
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class DistributionMatchingX(BaseQuantifier):
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class DMx(BaseQuantifier):
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"""
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Generic Distribution Matching quantifier for binary or multiclass quantification based on the space of covariates.
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This implementation takes the number of bins, the divergence, and the possibility to work on CDF as hyperparameters.
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@ -128,22 +52,51 @@ class DistributionMatchingX(BaseQuantifier):
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:param n_jobs: number of parallel workers (default None)
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"""
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def __init__(self, nbins=8, divergence: Union[str, Callable]='HD', cdf=False, n_jobs=None):
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def __init__(self, nbins=8, divergence: Union[str, Callable]='HD', cdf=False, search='optim_minimize', n_jobs=None):
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self.nbins = nbins
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self.divergence = divergence
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self.cdf = cdf
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self.search = search
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self.n_jobs = n_jobs
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@classmethod
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def HDx(cls, n_jobs=None):
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"""
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`Hellinger Distance x <https://www.sciencedirect.com/science/article/pii/S0020025512004069>`_ (HDx).
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HDx is a method for training binary quantifiers, that models quantification as the problem of
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minimizing the average divergence (in terms of the Hellinger Distance) across the feature-specific normalized
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histograms of two representations, one for the unlabelled examples, and another generated from the training
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examples as a mixture model of the class-specific representations. The parameters of the mixture thus represent
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the estimates of the class prevalence values.
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The method computes all matchings for nbins in [10, 20, ..., 110] and reports the mean of the median.
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The best prevalence is searched via linear search, from 0 to 1 stepping by 0.01.
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:param n_jobs: number of parallel workers
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:return: an instance of this class setup to mimick the performance of the HDx as originally proposed by
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González-Castro, Alaiz-Rodríguez, Alegre (2013)
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"""
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from quapy.method.meta import MedianEstimator
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dmx = DMx(divergence='HD', cdf=False, search='linear_search')
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nbins = {'nbins': np.linspace(10, 110, 11, dtype=int)}
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hdx = MedianEstimator(base_quantifier=dmx, param_grid=nbins, n_jobs=n_jobs)
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return hdx
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def __get_distributions(self, X):
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histograms = []
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for feat_idx in range(self.nfeats):
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hist = np.histogram(X[:, feat_idx], bins=self.nbins, range=self.feat_ranges[feat_idx])[0]
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normhist = hist / hist.sum()
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histograms.append(normhist)
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feature = X[:, feat_idx]
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feat_range = self.feat_ranges[feat_idx]
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hist = np.histogram(feature, bins=self.nbins, range=feat_range)[0]
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norm_hist = hist / hist.sum()
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histograms.append(norm_hist)
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distributions = np.vstack(histograms)
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if self.cdf:
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distributions = np.cumsum(distributions, axis=1)
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return distributions
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def fit(self, data: LabelledCollection):
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@ -184,20 +137,14 @@ class DistributionMatchingX(BaseQuantifier):
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test_distribution = self.__get_distributions(instances)
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divergence = get_divergence(self.divergence)
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n_classes, n_feats, nbins = self.validation_distribution.shape
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def match(prev):
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def loss(prev):
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prev = np.expand_dims(prev, axis=0)
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mixture_distribution = (prev @ self.validation_distribution.reshape(n_classes,-1)).reshape(n_feats, -1)
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divs = [divergence(test_distribution[feat], mixture_distribution[feat]) for feat in range(n_feats)]
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return np.mean(divs)
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# the initial point is set as the uniform distribution
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uniform_distribution = np.full(fill_value=1 / n_classes, shape=(n_classes,))
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return F.argmin_prevalence(loss, n_classes, method=self.search)
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# solutions are bounded to those contained in the unit-simplex
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bounds = tuple((0, 1) for x in range(n_classes)) # values in [0,1]
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constraints = ({'type': 'eq', 'fun': lambda x: 1 - sum(x)}) # values summing up to 1
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r = optimize.minimize(match, x0=uniform_distribution, method='SLSQP', bounds=bounds, constraints=constraints)
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return r.x
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def _get_features_range(X):
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@ -207,3 +154,10 @@ def _get_features_range(X):
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feature = X[:,col_idx]
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feat_ranges.append((np.min(feature), np.max(feature)))
|
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return feat_ranges
|
||||
|
||||
|
||||
#---------------------------------------------------------------
|
||||
# aliases
|
||||
#---------------------------------------------------------------
|
||||
|
||||
DistributionMatchingX = DMx
|
||||
|
|
@ -10,7 +10,7 @@ from quapy.data import Dataset, LabelledCollection
|
|||
from quapy.method import AGGREGATIVE_METHODS, NON_AGGREGATIVE_METHODS
|
||||
from quapy.method.meta import Ensemble
|
||||
from quapy.protocol import APP
|
||||
from quapy.method.aggregative import DistributionMatching
|
||||
from quapy.method.aggregative import DMy
|
||||
from quapy.method.meta import MedianEstimator
|
||||
|
||||
datasets = [pytest.param(qp.datasets.fetch_twitter('hcr', pickle=True), id='hcr'),
|
||||
|
|
@ -189,7 +189,7 @@ def test_median_meta():
|
|||
errors = []
|
||||
for nbins in nbins_grid:
|
||||
with qp.util.temp_seed(0):
|
||||
q = DistributionMatching(LogisticRegression(), nbins=nbins)
|
||||
q = DMy(LogisticRegression(), nbins=nbins)
|
||||
mae, estim_prevs = __fit_test(q, train, test)
|
||||
prevs.append(estim_prevs)
|
||||
errors.append(mae)
|
||||
|
|
@ -198,7 +198,7 @@ def test_median_meta():
|
|||
mae = np.mean(errors)
|
||||
print(f'\tMAE={mae:.4f}')
|
||||
|
||||
q = DistributionMatching(LogisticRegression())
|
||||
q = DMy(LogisticRegression())
|
||||
q = MedianEstimator(q, param_grid={'nbins': nbins_grid}, random_state=0, n_jobs=-1)
|
||||
median_mae, prev = __fit_test(q, train, test)
|
||||
print(f'\tMAE={median_mae:.4f}')
|
||||
|
|
@ -220,12 +220,12 @@ def test_median_meta_modsel():
|
|||
|
||||
nbins_grid = [2, 4, 5, 10, 15]
|
||||
|
||||
q = DistributionMatching(LogisticRegression())
|
||||
q = DMy(LogisticRegression())
|
||||
q = MedianEstimator(q, param_grid={'nbins': nbins_grid}, random_state=0, n_jobs=-1)
|
||||
median_mae, _ = __fit_test(q, train, test)
|
||||
print(f'\tMAE={median_mae:.4f}')
|
||||
|
||||
q = DistributionMatching(LogisticRegression())
|
||||
q = DMy(LogisticRegression())
|
||||
lr_params = {'classifier__C': np.logspace(-1, 1, 3)}
|
||||
q = MedianEstimator(q, param_grid={'nbins': nbins_grid}, random_state=0, n_jobs=-1)
|
||||
q = GridSearchQ(q, param_grid=lr_params, protocol=APP(val), n_jobs=-1)
|
||||
|
|
|
|||
Loading…
Reference in New Issue