diff --git a/TODO.txt b/TODO.txt
index 70b4c44..1c58be2 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -9,4 +9,18 @@ negative class). This is not covered in this new implementation, in which the bi
 an instance of single-label with 2 labels. Check
 Add classnames to LabelledCollection ?
 Check the overhead in OneVsAll for SVMperf-based (?)
-
+Add HDy to QuaNet? if so, wrap HDy into OneVsAll in case the dataset is not binary.
+Plots (one for binary -- the "diagonal", or for a specific class), another for the error as a funcition of drift.
+Add datasets for topic.
+Add other methods
+Clarify whether QuaNet is an aggregative method or not.
+Add datasets from Pérez-Gallego et al. 2017, 2019
+Add ensemble models from Pérez-Gallego et al. 2017, 2019
+Add plots models like those in Pérez-Gallego et al. 2017 (error boxes)
+Add support for CV prediction in ACC and PACC for tpr, fpr
+Add medium swap method
+Explore the hyperparameter "number of bins" in HDy
+Implement HDy for single-label?
+Rename EMQ to SLD ?
+How many times is the system of equations for ACC and PACC not solved? How many times is it clipped? Do they sum up
+    to one always?
\ No newline at end of file
diff --git a/quapy/__init__.py b/quapy/__init__.py
index e324da1..ac09f24 100644
--- a/quapy/__init__.py
+++ b/quapy/__init__.py
@@ -1,8 +1,8 @@
-from . import data
+from . import error
 from .data import datasets
 from . import functional
 from . import method
-from . import error
+from . import data
 from . import evaluation
 from method.aggregative import isaggregative, isprobabilistic
 
diff --git a/quapy/classification/methods.py b/quapy/classification/methods.py
new file mode 100644
index 0000000..997b3bc
--- /dev/null
+++ b/quapy/classification/methods.py
@@ -0,0 +1,38 @@
+from sklearn.decomposition import TruncatedSVD
+from sklearn.linear_model import LogisticRegression
+
+
+class PCALR:
+
+    def __init__(self, n_components=300, C=10, class_weight=None):
+        self.n_components = n_components
+        self.learner = LogisticRegression(C=C, class_weight=class_weight, max_iter=1000)
+
+    def get_params(self):
+        params = {'n_components': self.n_components}
+        params.update(self.learner.get_params())
+        return params
+
+    def set_params(self, **params):
+        if 'n_components' in params:
+            self.n_components = params['n_components']
+            del params['n_components']
+        self.learner.set_params(**params)
+
+    def fit(self, documents, labels):
+        self.pca = TruncatedSVD(self.n_components)
+        embedded = self.pca.fit_transform(documents, labels)
+        self.learner.fit(embedded, labels)
+        self.classes_ = self.learner.classes_
+        return self
+
+    def predict(self, documents):
+        embedded = self.transform(documents)
+        return self.learner.predict(embedded)
+
+    def predict_proba(self, documents):
+        embedded = self.transform(documents)
+        return self.learner.predict_proba(embedded)
+
+    def transform(self, documents):
+        return self.pca.transform(documents)
diff --git a/quapy/data/base.py b/quapy/data/base.py
index 6879a75..c75804e 100644
--- a/quapy/data/base.py
+++ b/quapy/data/base.py
@@ -1,11 +1,9 @@
 import numpy as np
 from scipy.sparse import issparse
 from sklearn.model_selection import train_test_split
-from quapy.functional import artificial_prevalence_sampling
+from quapy.functional import artificial_prevalence_sampling, strprev
 from scipy.sparse import vstack
 
-from util import temp_seed
-
 
 class LabelledCollection:
 
@@ -130,6 +128,21 @@ class LabelledCollection:
         labels = np.concatenate([self.labels, other.labels])
         return LabelledCollection(join_instances, labels)
 
+    @property
+    def Xy(self):
+        return self.instances, self.labels
+
+    def stats(self):
+        ninstances = len(self)
+        instance_type = type(self.instances[0])
+        if instance_type == list:
+            nfeats = len(self.instances[0])
+        elif instance_type == np.ndarray:
+            nfeats = self.instances.shape[1]
+        else:
+            nfeats = '?'
+        print(f'#instances={ninstances}, type={instance_type}, features={nfeats}, n_classes={self.n_classes}, '
+              f'prevs={strprev(self.prevalence())}')
 
 
 class Dataset:
@@ -153,7 +166,7 @@ class Dataset:
         return self.training.binary
 
     @classmethod
-    def load(cls, train_path, test_path, loader_func:callable):
+    def load(cls, train_path, test_path, loader_func: callable):
         training = LabelledCollection.load(train_path, loader_func)
         test = LabelledCollection.load(test_path, loader_func)
         return Dataset(training, test)
diff --git a/quapy/data/datasets.py b/quapy/data/datasets.py
index e2def20..0ef233e 100644
--- a/quapy/data/datasets.py
+++ b/quapy/data/datasets.py
@@ -2,13 +2,15 @@ import zipfile
 from util import download_file_if_not_exists, download_file, get_quapy_home, pickled_resource
 import os
 from os.path import join
-from data.base import Dataset
-from data.reader import from_text, from_sparse
+from data.base import Dataset, LabelledCollection
+from data.reader import *
 from data.preprocessing import text2tfidf, reduce_columns
+import pandas as pd
 
 
 REVIEWS_SENTIMENT_DATASETS = ['hp', 'kindle', 'imdb']
-TWITTER_SENTIMENT_DATASETS = ['gasp', 'hcr', 'omd', 'sanders', 'semeval13', 'semeval14', 'semeval15', 'semeval16',
+TWITTER_SENTIMENT_DATASETS = ['gasp', 'hcr', 'omd', 'sanders',
+                              'semeval13', 'semeval14', 'semeval15', 'semeval16',
                               'sst', 'wa', 'wb']
 
 
@@ -117,4 +119,88 @@ def fetch_twitter(dataset_name, for_model_selection=False, min_df=None, data_hom
     return data
 
 
+UCI_DATASETS = ['acute.a', 'acute.b',
+                'balance.1', 'balance.2', 'balance.3']
 
+def fetch_UCIDataset(dataset_name, data_home=None, verbose=False):
+
+    assert dataset_name in UCI_DATASETS, \
+        f'Name {dataset_name} does not match any known dataset from the UCI Machine Learning datasets repository. ' \
+        f'Valid ones are {UCI_DATASETS}'
+    if data_home is None:
+        data_home = get_quapy_home()
+
+    identifier_map = {
+        'acute.a': 'acute',
+        'acute.b': 'acute',
+        'balance.1': 'balance-scale',
+        'balance.2': 'balance-scale',
+        'balance.3': 'balance-scale',
+    }
+
+    dataset_fullname = {
+        'acute.a': 'Acute Inflammations (urinary bladder)',
+        'acute.b': 'Acute Inflammations (renal pelvis)',
+        'balance.1': 'Balance Scale Weight & Distance Database (left)',
+        'balance.2': 'Balance Scale Weight & Distance Database (balanced)',
+        'balance.3': 'Balance Scale Weight & Distance Database (right)',
+    }
+
+    data_folder = {
+        'acute': 'diagnosis',
+        'balance-scale': 'balance-scale',
+    }
+
+    identifier = identifier_map[dataset_name]
+    URL = f'http://archive.ics.uci.edu/ml/machine-learning-databases/{identifier}'
+    data_path = join(data_home, 'uci_datasets', identifier)
+    download_file_if_not_exists(f'{URL}/{data_folder[identifier]}.data', f'{data_path}/{identifier}.data')
+    download_file_if_not_exists(f'{URL}/{data_folder[identifier]}.names', f'{data_path}/{identifier}.names')
+
+    if verbose:
+        print(open(f'{data_path}/{identifier}.names', 'rt').read())
+
+    print(f'Loading {dataset_name} ({dataset_fullname[dataset_name]})')
+    if identifier == 'acute':
+        df = pd.read_csv(f'{data_path}/{identifier}.data', header=None, encoding='utf-16', sep='\t')
+        if dataset_name == 'acute.a':
+            y = binarize(df[6], pos_class='yes')
+        elif dataset_name == 'acute.b':
+            y = binarize(df[7], pos_class='yes')
+
+        mintemp, maxtemp = 35, 42
+        df[0] = df[0].apply(lambda x:(float(x.replace(',','.'))-mintemp)/(maxtemp-mintemp)).astype(float, copy=False)
+        [df_replace(df, col) for col in range(1, 6)]
+        X = df.loc[:, 0:5].values
+
+    if identifier == 'balance-scale':
+        df = pd.read_csv(f'{data_path}/{identifier}.data', header=None, sep=',')
+        if dataset_name == 'balance.1':
+            y = binarize(df[0], pos_class='L')
+        elif dataset_name == 'balance.2':
+            y = binarize(df[0], pos_class='B')
+        elif dataset_name == 'balance.3':
+            y = binarize(df[0], pos_class='R')
+        X = df.loc[:, 1:].astype(float).values
+
+    data = LabelledCollection(X, y)
+    data.stats()
+    #print(df)
+    #print(df.loc[:, 0:5].values)
+    #print(y)
+
+#    X = __read_csv(f'{data_path}/{identifier}.data', separator='\t')
+#    print(X)
+
+    #X, y = from_csv(f'{data_path}/{dataset_name}.data')
+    #y, classnames = reindex_labels(y)
+
+
+#def __read_csv(path, separator=','):
+#    x = []
+#    for instance in tqdm(open(path, 'rt', encoding='utf-16').readlines(), desc=f'reading {path}'):
+#        x.append(instance.strip().split(separator))
+#    return x
+
+def df_replace(df, col, repl={'yes': 1, 'no':0}, astype=float):
+    df[col] = df[col].apply(lambda x:repl[x]).astype(astype, copy=False)
\ No newline at end of file
diff --git a/quapy/data/reader.py b/quapy/data/reader.py
index 84550c6..7597fd0 100644
--- a/quapy/data/reader.py
+++ b/quapy/data/reader.py
@@ -1,6 +1,7 @@
 import numpy as np
 from scipy.sparse import dok_matrix
 from tqdm import tqdm
+import pandas as pd
 
 
 def from_text(path):
@@ -55,3 +56,42 @@ def from_sparse(path):
     y = np.asarray(all_labels) + 1
     return X, y
 
+
+def from_csv(path):
+    """
+    Reas a csv file in which columns are separated by ','.
+    File fomart <label>,<feat1>,<feat2>,...,<featn>\n
+    :param path: path to the csv file
+    :return: a ndarray for the labels and a ndarray (float) for the covariates
+    """
+
+    X, y = [], []
+    for instance in tqdm(open(path, 'rt').readlines(), desc=f'reading {path}'):
+        yi, *xi = instance.strip().split(',')
+        X.append(list(map(float,xi)))
+        y.append(yi)
+    X = np.asarray(X)
+    y = np.asarray(y)
+    return X, y
+
+
+def reindex_labels(y):
+    """
+    Re-indexes a list of labels as a list of indexes, and returns the classnames corresponding to the indexes.
+    E.g., y=['B', 'B', 'A', 'C'] -> [1,1,0,2], ['A','B','C']
+    :param y: the list or array of original labels
+    :return: a ndarray (int) of class indexes, and a ndarray of classnames corresponding to the indexes.
+    """
+    classnames = sorted(np.unique(y))
+    label2index = {label: index for index, label in enumerate(classnames)}
+    indexed = np.empty(y.shape, dtype=np.int)
+    for label in classnames:
+        indexed[y==label] = label2index[label]
+    return indexed, classnames
+
+
+def binarize(y, pos_class):
+    y = np.asarray(y)
+    ybin = np.zeros(y.shape, dtype=np.int)
+    ybin[y == pos_class] = 1
+    return ybin
\ No newline at end of file
diff --git a/quapy/error.py b/quapy/error.py
index fe6f3ec..e39aa8a 100644
--- a/quapy/error.py
+++ b/quapy/error.py
@@ -77,6 +77,9 @@ def __check_eps(eps):
 
 CLASSIFICATION_ERROR = {f1e, acce}
 QUANTIFICATION_ERROR = {mae, mrae, mse, mkld, mnkld}
+CLASSIFICATION_ERROR_NAMES = {func.__name__ for func in CLASSIFICATION_ERROR}
+QUANTIFICATION_ERROR_NAMES = {func.__name__ for func in QUANTIFICATION_ERROR}
+ERROR_NAMES = CLASSIFICATION_ERROR_NAMES | QUANTIFICATION_ERROR_NAMES
 
 f1_error = f1e
 acc_error = acce
diff --git a/quapy/evaluation.py b/quapy/evaluation.py
index c29f79c..4c56b1e 100644
--- a/quapy/evaluation.py
+++ b/quapy/evaluation.py
@@ -1,10 +1,12 @@
+from typing import Union, Callable, Iterable
 from data import LabelledCollection
-from quapy.method.aggregative import AggregativeQuantifier, AggregativeProbabilisticQuantifier
+from method.aggregative import AggregativeQuantifier, AggregativeProbabilisticQuantifier
 from method.base import BaseQuantifier
 from util import temp_seed
 import numpy as np
 from joblib import Parallel, delayed
 from tqdm import tqdm
+import error
 
 
 def artificial_sampling_prediction(
@@ -64,5 +66,19 @@ def artificial_sampling_prediction(
     return true_prevalences, estim_prevalences
 
 
+def evaluate(model: BaseQuantifier, test_samples:Iterable[LabelledCollection], err:Union[str, Callable], n_jobs:int=-1):
+    if isinstance(err, str):
+        err = getattr(error, err)
+    assert err.__name__ in error.QUANTIFICATION_ERROR_NAMES, \
+        f'error={err} does not seem to be a quantification error'
+    scores = Parallel(n_jobs=n_jobs)(
+        delayed(_delayed_eval)(model, Ti, err) for Ti in test_samples
+    )
+    return np.mean(scores)
 
 
+def _delayed_eval(model:BaseQuantifier, test:LabelledCollection, error:Callable):
+    prev_estim = model.quantify(test.instances)
+    prev_true  = test.prevalence()
+    return error(prev_true, prev_estim)
+
diff --git a/quapy/functional.py b/quapy/functional.py
index 17966b5..579e738 100644
--- a/quapy/functional.py
+++ b/quapy/functional.py
@@ -57,6 +57,37 @@ def prevalence_from_probabilities(posteriors, binarize: bool = False):
         return prevalences
 
 
+def HellingerDistance(P, Q):
+    return np.sqrt(np.sum((np.sqrt(P) - np.sqrt(Q))**2))
+
+
+#def uniform_simplex_sampling(n_classes):
+    # from https://cs.stackexchange.com/questions/3227/uniform-sampling-from-a-simplex
+#    r = [0.] + sorted(np.random.rand(n_classes-1)) + [1.]
+#    return np.asarray([b-a for a,b in zip(r[:-1],r[1:])])
+
+
+
+def uniform_prevalence_sampling(n_classes, size=1):
+    if n_classes == 2:
+        u = np.random.rand(size)
+        u = np.vstack([1-u, u]).T
+    else:
+        # from https://cs.stackexchange.com/questions/3227/uniform-sampling-from-a-simplex
+        u = np.random.rand(size, n_classes-1)
+        u.sort(axis=-1)
+        _0s = np.zeros(shape=(size, 1))
+        _1s = np.ones(shape=(size, 1))
+        a = np.hstack([_0s, u])
+        b = np.hstack([u, _1s])
+        u = b-a
+    if size == 1:
+        u = u.flatten()
+    return u
+        #return np.asarray([uniform_simplex_sampling(n_classes) for _ in range(size)])
+
+uniform_simplex_sampling = uniform_prevalence_sampling
+
 def strprev(prevalences, prec=3):
     return '['+ ', '.join([f'{p:.{prec}f}' for p in prevalences]) + ']'
 
@@ -72,14 +103,17 @@ def adjusted_quantification(prevalence_estim, tpr, fpr, clip=True):
 
 
 def normalize_prevalence(prevalences):
-    assert prevalences.ndim==1, 'unexpected shape'
-    accum = prevalences.sum()
-    if accum > 0:
-        return prevalences / accum
-    else:
-        # if all classifiers are trivial rejectors
-        return np.ones_like(prevalences) / prevalences.size
-
+    prevalences = np.asarray(prevalences)
+    n_classes = prevalences.shape[-1]
+    accum = prevalences.sum(axis=-1, keepdims=True)
+    prevalences = np.true_divide(prevalences, accum, where=accum>0)
+    allzeros = accum.flatten()==0
+    if any(allzeros):
+        if prevalences.ndim == 1:
+            prevalences = np.full(shape=n_classes, fill_value=1./n_classes)
+        else:
+            prevalences[accum.flatten()==0] = np.full(shape=n_classes, fill_value=1./n_classes)
+    return prevalences
 
 
 def num_prevalence_combinations(n_prevpoints:int, n_classes:int, n_repeats:int=1):
diff --git a/quapy/method/__init__.py b/quapy/method/__init__.py
index 88acd16..f6bc8d5 100644
--- a/quapy/method/__init__.py
+++ b/quapy/method/__init__.py
@@ -1,23 +1,28 @@
 from . import base
-from . import aggregative as agg
+from . import aggregative
 from . import non_aggregative
+from . import meta
 
 
 AGGREGATIVE_METHODS = {
-    agg.ClassifyAndCount,
-    agg.AdjustedClassifyAndCount,
-    agg.ProbabilisticClassifyAndCount,
-    agg.ProbabilisticAdjustedClassifyAndCount,
-    agg.ExplicitLossMinimisation,
-    agg.ExpectationMaximizationQuantifier,
-    agg.HellingerDistanceY
+    aggregative.ClassifyAndCount,
+    aggregative.AdjustedClassifyAndCount,
+    aggregative.ProbabilisticClassifyAndCount,
+    aggregative.ProbabilisticAdjustedClassifyAndCount,
+    aggregative.ExplicitLossMinimisation,
+    aggregative.ExpectationMaximizationQuantifier,
+    aggregative.HellingerDistanceY
 }
 
 NON_AGGREGATIVE_METHODS = {
     non_aggregative.MaximumLikelihoodPrevalenceEstimation
 }
 
-QUANTIFICATION_METHODS = AGGREGATIVE_METHODS | NON_AGGREGATIVE_METHODS
+META_METHODS = {
+    meta.QuaNet
+}
+
+QUANTIFICATION_METHODS = AGGREGATIVE_METHODS | NON_AGGREGATIVE_METHODS | META_METHODS
 
 
 
diff --git a/quapy/method/aggregative.py b/quapy/method/aggregative.py
index 8d18739..c973613 100644
--- a/quapy/method/aggregative.py
+++ b/quapy/method/aggregative.py
@@ -2,7 +2,7 @@ import numpy as np
 from copy import deepcopy
 import functional as F
 import error
-from method.base import BaseQuantifier
+from method.base import BaseQuantifier, BinaryQuantifier
 from classification.svmperf import SVMperf
 from data import LabelledCollection
 from sklearn.metrics import confusion_matrix
@@ -22,7 +22,7 @@ class AggregativeQuantifier(BaseQuantifier):
     """
 
     @abstractmethod
-    def fit(self, data: LabelledCollection, fit_learner=True, *args): ...
+    def fit(self, data: LabelledCollection, fit_learner=True): ...
 
     @property
     def learner(self):
@@ -35,12 +35,12 @@ class AggregativeQuantifier(BaseQuantifier):
     def classify(self, instances):
         return self.learner.predict(instances)
 
-    def quantify(self, instances, *args):
+    def quantify(self, instances):
         classif_predictions = self.classify(instances)
-        return self.aggregate(classif_predictions, *args)
+        return self.aggregate(classif_predictions)
 
     @abstractmethod
-    def aggregate(self, classif_predictions:np.ndarray, *args): ...
+    def aggregate(self, classif_predictions:np.ndarray): ...
 
     def get_params(self, deep=True):
         return self.learner.get_params()
@@ -68,9 +68,9 @@ class AggregativeProbabilisticQuantifier(AggregativeQuantifier):
     def posterior_probabilities(self, data):
         return self.learner.predict_proba(data)
 
-    def quantify(self, instances, *args):
+    def quantify(self, instances):
         classif_posteriors = self.posterior_probabilities(instances)
-        return self.aggregate(classif_posteriors, *args)
+        return self.aggregate(classif_posteriors)
 
     def set_params(self, **parameters):
         if isinstance(self.learner, CalibratedClassifierCV):
@@ -78,11 +78,6 @@ class AggregativeProbabilisticQuantifier(AggregativeQuantifier):
         self.learner.set_params(**parameters)
 
 
-class BinaryQuantifier(BaseQuantifier):
-    def _check_binary(self, data : LabelledCollection, quantifier_name):
-        assert data.binary, f'{quantifier_name} works only on problems of binary classification. ' \
-                            f'Use the class OneVsAll to enable {quantifier_name} work on single-label data.'
-
 
 # Helper
 # ------------------------------------
@@ -144,18 +139,17 @@ class ClassifyAndCount(AggregativeQuantifier):
     def __init__(self, learner):
         self.learner = learner
 
-    def fit(self, data: LabelledCollection, fit_learner=True, *args):
+    def fit(self, data: LabelledCollection, fit_learner=True):
         """
         Trains the Classify & Count method unless _fit_learner_ is False, in which case it is assumed to be already fit.
         :param data: training data
         :param fit_learner: if False, the classifier is assumed to be fit
-        :param args: unused
         :return: self
         """
         self.learner, _ = training_helper(self.learner, data, fit_learner)
         return self
 
-    def aggregate(self, classif_predictions, *args):
+    def aggregate(self, classif_predictions):
         return F.prevalence_from_labels(classif_predictions, self.n_classes)
 
 
@@ -186,7 +180,7 @@ class AdjustedClassifyAndCount(AggregativeQuantifier):
     def classify(self, data):
         return self.cc.classify(data)
 
-    def aggregate(self, classif_predictions, *args):
+    def aggregate(self, classif_predictions):
         prevs_estim = self.cc.aggregate(classif_predictions)
         return AdjustedClassifyAndCount.solve_adjustment(self.Pte_cond_estim_, prevs_estim)
 
@@ -208,11 +202,11 @@ class ProbabilisticClassifyAndCount(AggregativeProbabilisticQuantifier):
     def __init__(self, learner):
         self.learner = learner
 
-    def fit(self, data : LabelledCollection, fit_learner=True, *args):
+    def fit(self, data : LabelledCollection, fit_learner=True):
         self.learner, _ = training_helper(self.learner, data, fit_learner, ensure_probabilistic=True)
         return self
 
-    def aggregate(self, classif_posteriors, *args):
+    def aggregate(self, classif_posteriors):
         return F.prevalence_from_probabilities(classif_posteriors, binarize=False)
 
 
@@ -235,14 +229,22 @@ class ProbabilisticAdjustedClassifyAndCount(AggregativeProbabilisticQuantifier):
             self.learner, data, fit_learner, ensure_probabilistic=True, val_split=val_split
         )
         self.pcc = ProbabilisticClassifyAndCount(self.learner)
-        y_ = self.classify(validation.instances)
-        y = validation.labels
+        y_ = self.soft_classify(validation.instances)
+        y  = validation.labels
+        confusion = np.empty(shape=(data.n_classes, data.n_classes))
+        for yi in range(data.n_classes):
+            confusion[yi] = y_[y==yi].mean(axis=0)
+
+        self.Pte_cond_estim_ = confusion.T
+
+        #y_ = self.classify(validation.instances)
+        #y = validation.labels
         # estimate the matrix with entry (i,j) being the estimate of P(yi|yj), that is, the probability that a
         # document that belongs to yj ends up being classified as belonging to yi
-        self.Pte_cond_estim_ = confusion_matrix(y, y_).T / validation.counts()
+        #self.Pte_cond_estim_ = confusion_matrix(y, y_).T / validation.counts()
         return self
 
-    def aggregate(self, classif_posteriors, *args):
+    def aggregate(self, classif_posteriors):
         prevs_estim = self.pcc.aggregate(classif_posteriors)
         return AdjustedClassifyAndCount.solve_adjustment(self.Pte_cond_estim_, prevs_estim)
 
@@ -261,7 +263,7 @@ class ExpectationMaximizationQuantifier(AggregativeProbabilisticQuantifier):
     def __init__(self, learner):
         self.learner = learner
 
-    def fit(self, data: LabelledCollection, fit_learner=True, *args):
+    def fit(self, data: LabelledCollection, fit_learner=True):
         self.learner, _ = training_helper(self.learner, data, fit_learner, ensure_probabilistic=True)
         self.train_prevalence = F.prevalence_from_labels(data.labels, self.n_classes)
         return self
@@ -320,20 +322,20 @@ class HellingerDistanceY(AggregativeProbabilisticQuantifier, BinaryQuantifier):
         self._check_binary(data, self.__class__.__name__)
         self.learner, validation = training_helper(
             self.learner, data, fit_learner, ensure_probabilistic=True, val_split=val_split)
-        Px = self.posterior_probabilities(validation.instances)
+        Px = self.posterior_probabilities(validation.instances)[:,1]  # takes only the P(y=+1|x)
         self.Pxy1 = Px[validation.labels == 1]
         self.Pxy0 = Px[validation.labels == 0]
         return self
 
-    def aggregate(self, classif_posteriors, *args):
+    def aggregate(self, classif_posteriors):
         # "In this work, the number of bins b used in HDx and HDy was chosen from 10 to 110 in steps of 10,
         # and the final estimated a priori probability was taken as the median of these 11 estimates."
         # (González-Castro, et al., 2013).
 
-        Px = classif_posteriors
+        Px = classif_posteriors[:,1]  # takes only the P(y=+1|x)
 
         prev_estimations = []
-        for bins in np.linspace(10, 110, 11, dtype=int): #[10, 20, 30, ..., 100, 110]
+        for bins in np.linspace(10, 110, 11, dtype=int):  #[10, 20, 30, ..., 100, 110]
             Pxy0_density, _ = np.histogram(self.Pxy0, bins=bins, range=(0, 1), density=True)
             Pxy1_density, _ = np.histogram(self.Pxy1, bins=bins, range=(0, 1), density=True)
 
@@ -342,7 +344,7 @@ class HellingerDistanceY(AggregativeProbabilisticQuantifier, BinaryQuantifier):
             prev_selected, min_dist = None, None
             for prev in F.prevalence_linspace(n_prevalences=100, repeat=1, smooth_limits_epsilon=0.0):
                 Px_train = prev*Pxy1_density + (1 - prev)*Pxy0_density
-                hdy = HellingerDistanceY.HellingerDistance(Px_train, Px_test)
+                hdy = F.HellingerDistance(Px_train, Px_test)
                 if prev_selected is None or hdy < min_dist:
                     prev_selected, min_dist = prev, hdy
             prev_estimations.append(prev_selected)
@@ -350,10 +352,6 @@ class HellingerDistanceY(AggregativeProbabilisticQuantifier, BinaryQuantifier):
         pos_class_prev = np.median(prev_estimations)
         return np.asarray([1-pos_class_prev, pos_class_prev])
 
-    @classmethod
-    def HellingerDistance(cls, P, Q):
-        return np.sqrt(np.sum((np.sqrt(P) - np.sqrt(Q))**2))
-
 
 class ExplicitLossMinimisation(AggregativeQuantifier, BinaryQuantifier):
 
@@ -362,13 +360,13 @@ class ExplicitLossMinimisation(AggregativeQuantifier, BinaryQuantifier):
         self.loss = loss
         self.kwargs = kwargs
 
-    def fit(self, data: LabelledCollection, fit_learner=True, *args):
+    def fit(self, data: LabelledCollection, fit_learner=True):
         self._check_binary(data, self.__class__.__name__)
         assert fit_learner, 'the method requires that fit_learner=True'
         self.learner = SVMperf(self.svmperf_base, loss=self.loss, **self.kwargs).fit(data.instances, data.labels)
         return self
 
-    def aggregate(self, classif_predictions:np.ndarray, *args):
+    def aggregate(self, classif_predictions:np.ndarray):
         return F.prevalence_from_labels(classif_predictions, self.learner.n_classes_)
 
     def classify(self, X, y=None):
@@ -423,23 +421,24 @@ class OneVsAll(AggregativeQuantifier):
         self.binary_quantifier = binary_quantifier
         self.n_jobs = n_jobs
 
-    def fit(self, data: LabelledCollection, **kwargs):
+    def fit(self, data: LabelledCollection, fit_learner=True):
         assert not data.binary, \
             f'{self.__class__.__name__} expect non-binary data'
         assert isinstance(self.binary_quantifier, BaseQuantifier), \
             f'{self.binary_quantifier} does not seem to be a Quantifier'
+        assert fit_learner==True, 'fit_learner must be True'
         if not isinstance(self.binary_quantifier, BinaryQuantifier):
             raise ValueError(f'{self.binary_quantifier.__class__.__name__} does not seem to be an instance of '
                              f'{BinaryQuantifier.__class__.__name__}')
         self.dict_binary_quantifiers = {c: deepcopy(self.binary_quantifier) for c in data.classes_}
-        self.__parallel(self._delayed_binary_fit, data, **kwargs)
+        self.__parallel(self._delayed_binary_fit, data)
         return self
 
     def classify(self, instances):
         classif_predictions_bin = self.__parallel(self._delayed_binary_classification, instances)
         return classif_predictions_bin.T
 
-    def aggregate(self, classif_predictions_bin, *args):
+    def aggregate(self, classif_predictions_bin):
         assert set(np.unique(classif_predictions_bin)) == {0,1}, \
             'param classif_predictions_bin does not seem to be a valid matrix (ndarray) of binary ' \
             'predictions for each document (row) and class (columns)'
@@ -450,7 +449,7 @@ class OneVsAll(AggregativeQuantifier):
         #prevalences = np.asarray(prevalences)
         return F.normalize_prevalence(prevalences)
 
-    def quantify(self, X, *args):
+    def quantify(self, X):
         prevalences = self.__parallel(self._delayed_binary_quantify, X)
         return F.normalize_prevalence(prevalences)
 
@@ -480,9 +479,9 @@ class OneVsAll(AggregativeQuantifier):
     def _delayed_binary_aggregate(self, c, classif_predictions):
         return self.dict_binary_quantifiers[c].aggregate(classif_predictions[:,c])[1]  # the estimation for the positive class prevalence
 
-    def _delayed_binary_fit(self, c, data, **kwargs):
+    def _delayed_binary_fit(self, c, data):
         bindata = LabelledCollection(data.instances, data.labels == c, n_classes=2)
-        self.dict_binary_quantifiers[c].fit(bindata, **kwargs)
+        self.dict_binary_quantifiers[c].fit(bindata)
 
 
 def isaggregative(model):
@@ -497,5 +496,3 @@ def isbinary(model):
     return isinstance(model, BinaryQuantifier)
 
 
-from . import neural
-QuaNet = neural.QuaNetTrainer
\ No newline at end of file
diff --git a/quapy/method/base.py b/quapy/method/base.py
index 9561a27..6134dea 100644
--- a/quapy/method/base.py
+++ b/quapy/method/base.py
@@ -1,15 +1,18 @@
 from abc import ABCMeta, abstractmethod
+from data import LabelledCollection
 
 
 # Base Quantifier abstract class
 # ------------------------------------
+
+
 class BaseQuantifier(metaclass=ABCMeta):
 
     @abstractmethod
-    def fit(self, data, *args): ...
+    def fit(self, data): ...
 
     @abstractmethod
-    def quantify(self, instances, *args): ...
+    def quantify(self, instances): ...
 
     @abstractmethod
     def set_params(self, **parameters): ...
@@ -18,6 +21,12 @@ class BaseQuantifier(metaclass=ABCMeta):
     def get_params(self, deep=True): ...
 
 
+class BinaryQuantifier(BaseQuantifier):
+    def _check_binary(self, data: LabelledCollection, quantifier_name):
+        assert data.binary, f'{quantifier_name} works only on problems of binary classification. ' \
+                            f'Use the class OneVsAll to enable {quantifier_name} work on single-label data.'
+
+
 # class OneVsAll(AggregativeQuantifier):
 #     """
 #     Allows any binary quantifier to perform quantification on single-label datasets. The method maintains one binary
diff --git a/quapy/method/meta.py b/quapy/method/meta.py
new file mode 100644
index 0000000..60bc145
--- /dev/null
+++ b/quapy/method/meta.py
@@ -0,0 +1,304 @@
+import numpy as np
+from sklearn.linear_model import LogisticRegressionCV, LogisticRegression
+
+import quapy as qp
+from sklearn.model_selection import GridSearchCV, cross_val_predict
+from model_selection import GridSearchQ
+from .base import BaseQuantifier, BinaryQuantifier
+from joblib import Parallel, delayed
+from copy import deepcopy
+from data import LabelledCollection
+from quapy import functional as F
+from . import neural
+from evaluation import evaluate
+
+QuaNet = neural.QuaNetTrainer
+
+
+class Ensemble(BaseQuantifier):
+
+    VALID_POLICIES = {'ave', 'ptr', 'ds'} | qp.error.QUANTIFICATION_ERROR_NAMES
+
+    """
+    Methods from the articles:
+    Pérez-Gállego, P., Quevedo, J. R., & del Coz, J. J. (2017).
+    Using ensembles for problems with characterizable changes in data distribution: A case study on quantification.
+    Information Fusion, 34, 87-100.
+    and
+    Pérez-Gállego, P., Castano, A., Quevedo, J. R., & del Coz, J. J. (2019). 
+    Dynamic ensemble selection for quantification tasks. 
+    Information Fusion, 45, 1-15.
+    """
+
+    def __init__(self, quantifier: BaseQuantifier, size=50, min_pos=1, red_size=25, policy='ave', n_jobs=1):
+        assert policy in Ensemble.VALID_POLICIES, f'unknown policy={policy}; valid are {Ensemble.VALID_POLICIES}'
+        self.base_quantifier = quantifier
+        self.size = size
+        self.min_pos = min_pos
+        self.red_size = red_size
+        self.policy = policy
+        self.n_jobs = n_jobs
+        self.post_proba_fn = None
+
+    def fit(self, data: LabelledCollection):
+        if self.policy=='ds' and not data.binary:
+            raise ValueError(f'ds policy is only defined for binary quantification, but this dataset is not binary')
+
+        # randomly chooses the prevalences for each member of the ensemble (preventing classes with less than
+        # min_pos positive examples)
+        prevs = [_draw_simplex(ndim=data.n_classes, min_val=self.min_pos / len(data)) for _ in range(self.size)]
+
+        posteriors = None
+        if self.policy == 'ds':
+            # precompute the training posterior probabilities
+            posteriors, self.post_proba_fn = self.ds_policy_get_posteriors(data)
+
+        is_static_policy = (self.policy in qp.error.QUANTIFICATION_ERROR_NAMES)
+        self.ensemble = Parallel(n_jobs=self.n_jobs)(
+            delayed(_delayed_new_instance)(
+                self.base_quantifier, data, prev, posteriors, keep_samples=is_static_policy
+            ) for prev in prevs
+        )
+
+#        self.ensemble = [deepcopy(self.base_quantifier) for _ in range(self.size)]
+#        self.prevs = [self._valid_simplex_sampling(data.n_classes, min_val=min_freq) for _ in range(self.size)]
+#        self.samples = [data.sampling(sample_size, *Pi) for Pi in self.prevs]
+
+#        Parallel(n_jobs=self.n_jobs)(
+#            delayed(_delayed_fit)(Qi, Si) for Si, Qi, in zip(self.samples, self.ensemble)
+#        )
+
+        # static selection policy (the name of a quantification-oriented error function to minimize)
+        if self.policy in qp.error.QUANTIFICATION_ERROR_NAMES:
+            self.accuracy_policy(error_name=self.policy)
+
+        return self
+
+    def quantify(self, instances):
+        predictions = np.asarray(Parallel(n_jobs=self.n_jobs)(
+            delayed(_delayed_quantify)(Qi, instances) for Qi in self.ensemble
+        ))
+
+        if self.policy == 'ptr':
+            predictions = self.ptr_policy(predictions)
+        elif self.policy == 'ds':
+            predictions = self.ds_policy(predictions, instances)
+
+        predictions = np.mean(predictions, axis=0)
+        return F.normalize_prevalence(predictions)
+
+    def set_params(self, **parameters):
+        raise NotImplementedError(f'{self.__class__.__name__} should not be used within GridSearchQ; '
+                                  f'instead, use GridSearchQ within Ensemble, or GridSearchCV whithin the '
+                                  f'base quantifier if it is an aggregative one.')
+
+    def get_params(self, deep=True):
+        raise NotImplementedError()
+
+    def accuracy_policy(self, error_name):
+        """
+        Selects the red_size best performant quantifiers in a static way (i.e., dropping all non-selected instances).
+        For each model in the ensemble, the performance is measured in terms of _error_name_ on the quantification of
+        the samples used for training the rest of the models in the ensemble.
+        """
+        error = getattr(qp.error, error_name)
+        tests = [m[3] for m in self.ensemble]
+        scores = []
+        for i, model in enumerate(self.ensemble):
+            scores.append(evaluate(model[0], tests[:i] + tests[i+1:], error, self.n_jobs))
+        order = np.argsort(scores)
+
+        self.ensemble = select_k(self.ensemble, order, k=self.red_size)
+
+    def ptr_policy(self, predictions):
+        """
+        Selects the predictions made by models that have been trained on samples with a prevalence that is most similar
+        to a first approximation of the test prevalence as made by all models in the ensemble.
+        """
+        test_prev_estim = predictions.mean(axis=0)
+        tr_prevs = [m[1] for m in self.ensemble]
+        ptr_differences = [qp.error.mse(ptr_i, test_prev_estim) for ptr_i in tr_prevs]
+        order = np.argsort(ptr_differences)
+        return select_k(predictions, order, k=self.red_size)
+
+    def ds_policy_get_posteriors(self, data: LabelledCollection):
+        """
+        In the original article, this procedure is not described in a sufficient level of detail. The paper only says
+        that the distribution of posterior probabilities from training and test examples is compared by means of the
+        Hellinger Distance. However, how these posterior probabilities are generated is not specified. In the article,
+        a Logistic Regressor (LR) is used as the classifier device and that could be used for this purpose. However, in
+        general, a Quantifier is not necessarily an instance of Aggreggative Probabilistic Quantifiers, and so that the
+        quantifier builds on top of a probabilistic classifier cannot be given for granted. Additionally, it would not
+        be correct to generate the posterior probabilities for training documents that have concurred in training the
+        classifier that generates them.
+        This function thus generates the posterior probabilities for all training documents in a cross-validation way,
+        using a LR with hyperparameters that have previously been optimized via grid search in 5FCV.
+        :return P,f, where P is a ndarray containing the posterior probabilities of the training data, generated via
+        cross-validation and using an optimized LR, and the function to be used in order to generate posterior
+        probabilities for test instances.
+        """
+        X, y = data.Xy
+        lr_base = LogisticRegression(class_weight='balanced', max_iter=1000)
+
+        optim = GridSearchCV(
+            lr_base, param_grid={'C': np.logspace(-4,4,9)}, cv=5, n_jobs=self.n_jobs, refit=True
+        ).fit(X, y)
+
+        posteriors = cross_val_predict(
+            optim.best_estimator_, X, y, cv=5, n_jobs=self.n_jobs, method='predict_proba'
+        )
+        posteriors_generator = optim.best_estimator_.predict_proba
+
+        return posteriors, posteriors_generator
+
+    def ds_policy(self, predictions, test):
+        test_posteriors = self.post_proba_fn(test)
+        test_distribution = get_probability_distribution(test_posteriors)
+        tr_distributions = [m[2] for m in self.ensemble]
+        dist = [F.HellingerDistance(tr_dist_i, test_distribution) for tr_dist_i in tr_distributions]
+        order = np.argsort(dist)
+        return select_k(predictions, order, k=self.red_size)
+
+
+def get_probability_distribution(posterior_probabilities, bins=8):
+    assert posterior_probabilities.shape[1]==2, 'the posterior probabilities do not seem to be for a binary problem'
+    posterior_probabilities = posterior_probabilities[:,1]  # take the positive posteriors only
+    distribution, _ = np.histogram(posterior_probabilities, bins=bins, range=(0, 1), density=True)
+    return distribution
+
+
+def select_k(elements, order, k):
+    return [elements[idx] for idx in order[:k]]
+
+
+def _delayed_new_instance(base_quantifier, data:LabelledCollection, prev, posteriors, keep_samples):
+    model = deepcopy(base_quantifier)
+    sample_index = data.sampling_index(len(data), *prev)
+    sample = data.sampling_from_index(sample_index)
+    model.fit(sample)
+    tr_prevalence = sample.prevalence()
+    tr_distribution = get_probability_distribution(posteriors[sample_index]) if (posteriors is not None) else None
+    return (model, tr_prevalence, tr_distribution, sample if keep_samples else None)
+
+
+def _delayed_fit(quantifier, data):
+    quantifier.fit(data)
+
+
+def _delayed_quantify(quantifier, instances):
+    return quantifier[0].quantify(instances)
+
+
+def _draw_simplex(ndim, min_val, max_trials=100):
+    """
+    returns a uniform sampling from the ndim-dimensional simplex but guarantees that all dimensions
+    are >= min_class_prev (for min_val>0, this makes the sampling not truly uniform)
+    :param ndim: number of dimensions of the simplex
+    :param min_val: minimum class prevalence allowed. If less than 1/ndim a ValueError will be throw since
+    there is no possible solution.
+    :return: a sample from the ndim-dimensional simplex that is uniform in S(ndim)-R where S(ndim) is the simplex
+    and R is the simplex subset containing dimensions lower than min_val
+    """
+    if min_val >= 1/ndim:
+        raise ValueError(f'no sample can be draw from the {ndim}-dimensional simplex so that '
+                         f'all its values are >={min_val} (try with a larger value for min_pos)')
+    trials = 0
+    while True:
+        u = F.uniform_simplex_sampling(ndim)
+        if all(u >= min_val):
+            return u
+        trials += 1
+        if trials >= max_trials:
+            raise ValueError(f'it looks like finding a random simplex with all its dimensions being'
+                             f'>= {min_val} is unlikely (it failed after {max_trials} trials)')
+
+
+def _instantiate_ensemble(learner, base_quantifier_class, param_grid, optim, sample_size, eval_budget, **kwargs):
+    if optim is None:
+        base_quantifier = base_quantifier_class(learner)
+    elif optim in qp.error.CLASSIFICATION_ERROR:
+        learner = GridSearchCV(learner, param_grid)
+        base_quantifier = base_quantifier_class(learner)
+    elif optim in qp.error.QUANTIFICATION_ERROR:
+        base_quantifier = GridSearchQ(base_quantifier_class(learner),
+                                      param_grid=param_grid,
+                                      sample_size=sample_size,
+                                      eval_budget=eval_budget,
+                                      error=optim)
+    else:
+        raise ValueError(f'value optim={optim} not understood')
+
+    return Ensemble(base_quantifier, **kwargs)
+
+
+class EnsembleFactory(BaseQuantifier):
+
+    def __init__(self, learner, base_quantifier_class, param_grid=None, optim=None, sample_size=None, eval_budget=None,
+                 size=50, min_pos=1, red_size=25, policy='ave', n_jobs=1):
+        if param_grid is None and optim is not None:
+            raise ValueError(f'param_grid is None but optim was requested.')
+        error = self._check_error(optim)
+        self.model = _instantiate_ensemble(learner, base_quantifier_class, param_grid, error, sample_size,
+                                           eval_budget, size=size, min_pos=min_pos, red_size=red_size,
+                                           policy=policy, n_jobs=n_jobs)
+
+    def fit(self, data):
+        return self.model.fit(data)
+
+    def quantify(self, instances):
+        return self.model.quantify(instances)
+
+    def set_params(self, **parameters):
+        return self.model.set_params(**parameters)
+
+    def get_params(self, deep=True):
+        return self.model.get_params(deep)
+
+    def _check_error(self, error):
+        if error is None:
+            return None
+        if error in qp.error.QUANTIFICATION_ERROR or error in qp.error.CLASSIFICATION_ERROR:
+            return error
+        elif isinstance(error, str):
+            assert error in qp.error.ERROR_NAMES, \
+                f'unknown error name; valid ones are {qp.error.ERROR_NAMES}'
+            return getattr(qp.error, error)
+        else:
+            raise ValueError(f'unexpected error type; must either be a callable function or a str representing\n'
+                             f'the name of an error function in {qp.error.ERROR_NAMES}')
+
+
+class ECC(EnsembleFactory):
+    def __init__(self, learner, param_grid=None, optim=None, sample_size=None, eval_budget=None,
+                 size=50, min_pos=1, red_size=25, policy='ave', n_jobs=1):
+        super().__init__(
+            learner, qp.method.aggregative.CC, param_grid, optim, sample_size, eval_budget, size, min_pos,
+            red_size, policy, n_jobs
+        )
+
+
+class EACC(EnsembleFactory):
+    def __init__(self, learner, param_grid=None, optim=None, sample_size=None, eval_budget=None,
+                 size=50, min_pos=1, red_size=25, policy='ave', n_jobs=1):
+        super().__init__(
+            learner, qp.method.aggregative.ACC, param_grid, optim, sample_size, eval_budget, size, min_pos,
+            red_size, policy, n_jobs
+        )
+
+
+class EHDy(EnsembleFactory):
+    def __init__(self, learner, param_grid=None, optim=None, sample_size=None, eval_budget=None,
+                 size=50, min_pos=1, red_size=25, policy='ave', n_jobs=1):
+        super().__init__(
+            learner, qp.method.aggregative.HDy, param_grid, optim, sample_size, eval_budget, size, min_pos,
+            red_size, policy, n_jobs
+        )
+
+
+class EEMQ(EnsembleFactory):
+    def __init__(self, learner, param_grid=None, optim=None, sample_size=None, eval_budget=None,
+                 size=50, min_pos=1, red_size=25, policy='ave', n_jobs=1):
+        super().__init__(
+            learner, qp.method.aggregative.EMQ, param_grid, optim, sample_size, eval_budget, size, min_pos,
+            red_size, policy, n_jobs
+        )
\ No newline at end of file
diff --git a/quapy/method/neural.py b/quapy/method/neural.py
index 0b4ff65..da4b35c 100644
--- a/quapy/method/neural.py
+++ b/quapy/method/neural.py
@@ -75,23 +75,26 @@ class QuaNetTrainer(BaseQuantifier):
         # estimate the hard and soft stats tpr and fpr of the classifier
         self.tr_prev = data.prevalence()
 
-        self.quantifiers = [
-            ClassifyAndCount(self.learner).fit(data, fit_learner=False),
-            AdjustedClassifyAndCount(self.learner).fit(data, fit_learner=False),
-            ProbabilisticClassifyAndCount(self.learner).fit(data, fit_learner=False),
-            ProbabilisticAdjustedClassifyAndCount(self.learner).fit(data, fit_learner=False),
-            ExpectationMaximizationQuantifier(self.learner).fit(data, fit_learner=False),
-        ]
+        self.quantifiers = {
+            'cc': ClassifyAndCount(self.learner).fit(data, fit_learner=False),
+            'acc': AdjustedClassifyAndCount(self.learner).fit(data, fit_learner=False),
+            'pcc': ProbabilisticClassifyAndCount(self.learner).fit(data, fit_learner=False),
+            'pacc': ProbabilisticAdjustedClassifyAndCount(self.learner).fit(data, fit_learner=False),
+            'emq': ExpectationMaximizationQuantifier(self.learner).fit(data, fit_learner=False),
+        }
 
         self.status = {
             'tr-loss': -1,
             'va-loss': -1,
         }
 
+        nQ = len(self.quantifiers)
+        nC = data.n_classes
         self.quanet = QuaNetModule(
             doc_embedding_size=train_data.instances.shape[1],
             n_classes=data.n_classes,
-            stats_size=len(self.quantifiers) * data.n_classes,
+            stats_size=nQ*nC + 2*nC*nC,
+            order_by=0 if data.binary else None,
             **self.quanet_params
         ).to(self.device)
 
@@ -119,10 +122,15 @@ class QuaNetTrainer(BaseQuantifier):
     def get_aggregative_estims(self, posteriors):
         label_predictions = np.argmax(posteriors, axis=-1)
         prevs_estim = []
-        for quantifier in self.quantifiers:
+        for quantifier in self.quantifiers.values():
             predictions = posteriors if isprobabilistic(quantifier) else label_predictions
-            prevs_estim.append(quantifier.aggregate(predictions))
-        return np.asarray(prevs_estim).flatten()
+            prevs_estim.extend(quantifier.aggregate(predictions))
+
+        # add the class-conditional predictions P(y'i|yj) from ACC and PACC
+        prevs_estim.extend(self.quantifiers['acc'].Pte_cond_estim_.flatten())
+        prevs_estim.extend(self.quantifiers['pacc'].Pte_cond_estim_.flatten())
+
+        return prevs_estim
 
     def quantify(self, instances, *args):
         posteriors = self.learner.predict_proba(instances)
diff --git a/quapy/model_selection.py b/quapy/model_selection.py
index 227987a..7731d2a 100644
--- a/quapy/model_selection.py
+++ b/quapy/model_selection.py
@@ -4,14 +4,14 @@ from evaluation import artificial_sampling_prediction
 from data.base import LabelledCollection
 from method.aggregative import BaseQuantifier
 from typing import Union, Callable
-import quapy.functional as F
+import functional as F
 from copy import deepcopy
 
 
-class GridSearchQ:
+class GridSearchQ(BaseQuantifier):
 
     def __init__(self,
-                 model : BaseQuantifier,
+                 model: BaseQuantifier,
                  param_grid: dict,
                  sample_size: int,
                  n_prevpoints: int = None,
@@ -105,14 +105,14 @@ class GridSearchQ:
         if error in qp.error.QUANTIFICATION_ERROR:
             self.error = error
         elif isinstance(error, str):
-            assert error in {func.__name__ for func in qp.error.QUANTIFICATION_ERROR}, \
-                f'unknown error name; valid ones are {qp.error.QUANTIFICATION_ERROR}'
+            assert error in qp.error.QUANTIFICATION_ERROR_NAMES, \
+                f'unknown error name; valid ones are {qp.error.QUANTIFICATION_ERROR_NAMES}'
             self.error = getattr(qp.error, error)
         else:
             raise ValueError(f'unexpected error type; must either be a callable function or a str representing\n'
-                             f'the name of an error function in {qp.error.QUANTIFICATION_ERROR}')
+                             f'the name of an error function in {qp.error.QUANTIFICATION_ERROR_NAMES}')
 
-    def fit(self, training: LabelledCollection, validation: Union[LabelledCollection, float]):
+    def fit(self, training: LabelledCollection, validation: Union[LabelledCollection, float]=0.3):
         """
         :param training: the training set on which to optimize the hyperparameters
         :param validation: either a LabelledCollection on which to test the performance of the different settings, or
@@ -158,5 +158,14 @@ class GridSearchQ:
             self.sout(f'refitting on the whole development set')
             self.best_model_.fit(training + validation)
 
-        return self.best_model_
+        return self
+
+    def quantify(self, instances):
+        return self.best_model_.quantify(instances)
+
+    def set_params(self, **parameters):
+        self.param_grid = parameters
+
+    def get_params(self, deep=True):
+        return self.param_grid
 
diff --git a/test.py b/test.py
index e8d9ebc..a9cff1d 100644
--- a/test.py
+++ b/test.py
@@ -1,45 +1,65 @@
 from sklearn.linear_model import LogisticRegression
+from sklearn.model_selection import GridSearchCV
 from sklearn.svm import LinearSVC
 import quapy as qp
 import quapy.functional as F
 import sys
 import numpy as np
+from classification.methods import PCALR
 from classification.neural import NeuralClassifierTrainer, CNNnet
 from quapy.model_selection import GridSearchQ
 
+
+
+#qp.datasets.fetch_UCIDataset('acute.b', verbose=True)
+
+#sys.exit(0)
 qp.environ['SAMPLE_SIZE'] = 500
+#param_grid = {'C': np.logspace(-3,3,7), 'class_weight': ['balanced', None]}
+param_grid = {'C': np.logspace(0,3,4), 'class_weight': ['balanced']}
+max_evaluations = 5000
 
 sample_size = qp.environ['SAMPLE_SIZE']
 binary = True
 svmperf_home = './svm_perf_quantification'
 
 if binary:
-    dataset = qp.datasets.fetch_reviews('kindle', tfidf=False, min_df=5)
-    qp.data.preprocessing.index(dataset, inplace=True)
+    dataset = qp.datasets.fetch_reviews('kindle', tfidf=True, min_df=5)
+    #qp.data.preprocessing.index(dataset, inplace=True)
 
 else:
     dataset = qp.datasets.fetch_twitter('hcr', for_model_selection=False, min_df=10, pickle=True)
-    # dataset.training = dataset.training.sampling(SAMPLE_SIZE, 0.2, 0.5, 0.3)
+    dataset.training = dataset.training.sampling(sample_size, 0.2, 0.5, 0.3)
 
 print(f'dataset loaded: #training={len(dataset.training)} #test={len(dataset.test)}')
 
 
 # training a quantifier
 # learner = LogisticRegression(max_iter=1000)
-# model = qp.method.aggregative.ClassifyAndCount(learner)
+#model = qp.method.aggregative.ClassifyAndCount(learner)
 # model = qp.method.aggregative.AdjustedClassifyAndCount(learner)
 # model = qp.method.aggregative.ProbabilisticClassifyAndCount(learner)
 # model = qp.method.aggregative.ProbabilisticAdjustedClassifyAndCount(learner)
+# model = qp.method.aggregative.HellingerDistanceY(learner)
 # model = qp.method.aggregative.ExpectationMaximizationQuantifier(learner)
 # model = qp.method.aggregative.ExplicitLossMinimisationBinary(svmperf_home, loss='q', C=100)
 # model = qp.method.aggregative.SVMQ(svmperf_home, C=1)
 
-learner = NeuralClassifierTrainer(CNNnet(dataset.vocabulary_size, dataset.n_classes))
-print(learner.get_params())
-model = qp.method.aggregative.QuaNet(learner, sample_size, device='cpu')
+#learner = PCALR()
+#learner = NeuralClassifierTrainer(CNNnet(dataset.vocabulary_size, dataset.n_classes))
+#print(learner.get_params())
+#model = qp.method.meta.QuaNet(learner, sample_size, device='cpu')
 
-if qp.isbinary(model) and not qp.isbinary(dataset):
-    model = qp.method.aggregative.OneVsAll(model)
+#learner = GridSearchCV(LogisticRegression(max_iter=1000), param_grid=param_grid, n_jobs=-1, verbose=1)
+learner = LogisticRegression(max_iter=1000)
+model = qp.method.meta.ECC(learner, size=20, red_size=10, param_grid=None, optim=None, policy='ds')
+#model = qp.method.meta.EHDy(learner, param_grid=param_grid, optim='mae',
+#                           sample_size=sample_size, eval_budget=max_evaluations//10, n_jobs=-1)
+#model = qp.method.aggregative.ClassifyAndCount(learner)
+
+
+#if qp.isbinary(model) and not qp.isbinary(dataset):
+#    model = qp.method.aggregative.OneVsAll(model)
 
 
 # Model fit and Evaluation on the test data
@@ -49,6 +69,10 @@ print(f'fitting model {model.__class__.__name__}')
 #train, val = dataset.training.split_stratified(0.6)
 #model.fit(train, val_split=val)
 model.fit(dataset.training)
+#for i,e in enumerate(model.ensemble):
+    #print(i, e.learner.best_estimator_)
+#    print(i, e.best_model_.learner)
+
 
 # estimating class prevalences
 print('quantifying')
@@ -67,7 +91,7 @@ print(f'mae={error:.3f}')
 # Model fit and Evaluation according to the artificial sampling protocol
 # ----------------------------------------------------------------------------
 
-max_evaluations = 5000
+
 n_prevpoints = F.get_nprevpoints_approximation(combinations_budget=max_evaluations, n_classes=dataset.n_classes)
 n_evaluations = F.num_prevalence_combinations(n_prevpoints, dataset.n_classes)
 print(f'the prevalence interval [0,1] will be split in {n_prevpoints} prevalence points for each class, so that\n'
@@ -76,7 +100,7 @@ print(f'the prevalence interval [0,1] will be split in {n_prevpoints} prevalence
 
 true_prev, estim_prev = qp.evaluation.artificial_sampling_prediction(model, dataset.test, sample_size, n_prevpoints)
 
-qp.error.SAMPLE_SIZE = sample_size
+#qp.error.SAMPLE_SIZE = sample_size
 print(f'Evaluation according to the artificial sampling protocol ({len(true_prev)} evals)')
 for error in qp.error.QUANTIFICATION_ERROR:
     score = error(true_prev, estim_prev)
@@ -86,7 +110,7 @@ for error in qp.error.QUANTIFICATION_ERROR:
 # Model selection and Evaluation according to the artificial sampling protocol
 # ----------------------------------------------------------------------------
 sys.exit(0)
-param_grid = {'C': np.logspace(-3,3,7), 'class_weight': ['balanced', None]}
+
 
 model_selection = GridSearchQ(model,
                               param_grid=param_grid,
@@ -96,8 +120,8 @@ model_selection = GridSearchQ(model,
                               refit=True,
                               verbose=True)
 
-# model = model_selection.fit(dataset.training, validation=0.3)
-model = model_selection.fit(train, validation=val)
+model = model_selection.fit(dataset.training, validation=0.3)
+#model = model_selection.fit(train, validation=val)
 print(f'Model selection: best_params = {model_selection.best_params_}')
 print(f'param scores:')
 for params, score in model_selection.param_scores_.items():