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Diffstat (limited to 'src/python/gudhi/representations/vector_methods.py')
-rw-r--r-- | src/python/gudhi/representations/vector_methods.py | 144 |
1 files changed, 141 insertions, 3 deletions
diff --git a/src/python/gudhi/representations/vector_methods.py b/src/python/gudhi/representations/vector_methods.py index 46fee086..5ca127f6 100644 --- a/src/python/gudhi/representations/vector_methods.py +++ b/src/python/gudhi/representations/vector_methods.py @@ -1,16 +1,17 @@ # This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT. # See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details. -# Author(s): Mathieu Carrière +# Author(s): Mathieu Carrière, Martin Royer # -# Copyright (C) 2018-2019 Inria +# Copyright (C) 2018-2020 Inria # # Modification(s): -# - YYYY/MM Author: Description of the modification +# - 2020/06 Martin: ATOL integration import numpy as np from sklearn.base import BaseEstimator, TransformerMixin from sklearn.preprocessing import MinMaxScaler, MaxAbsScaler from sklearn.neighbors import DistanceMetric +from sklearn.metrics import pairwise from .preprocessing import DiagramScaler, BirthPersistenceTransform @@ -574,3 +575,140 @@ class ComplexPolynomial(BaseEstimator, TransformerMixin): numpy array with shape (**threshold**): output complex vector of coefficients. """ return self.fit_transform([diag])[0,:] + +def _lapl_contrast(measure, centers, inertias): + """contrast function for vectorising `measure` in ATOL""" + return np.exp(-pairwise.pairwise_distances(measure, Y=centers) / inertias) + +def _gaus_contrast(measure, centers, inertias): + """contrast function for vectorising `measure` in ATOL""" + return np.exp(-pairwise.pairwise_distances(measure, Y=centers, squared=True) / inertias**2) + +def _indicator_contrast(diags, centers, inertias): + """contrast function for vectorising `measure` in ATOL""" + robe_curve = np.clip(2-pairwise.pairwise_distances(diags, Y=centers)/inertias, 0, 1) + return robe_curve + +def _cloud_weighting(measure): + """automatic uniform weighting with mass 1 for `measure` in ATOL""" + return np.ones(shape=measure.shape[0]) + +def _iidproba_weighting(measure): + """automatic uniform weighting with mass 1/N for `measure` in ATOL""" + return np.ones(shape=measure.shape[0]) / measure.shape[0] + +class Atol(BaseEstimator, TransformerMixin): + """ + This class allows to vectorise measures (e.g. point clouds, persistence diagrams, etc) after a quantisation step. + + ATOL paper: :cite:`royer2019atol` + + Example + -------- + >>> from sklearn.cluster import KMeans + >>> from gudhi.representations.vector_methods import Atol + >>> import numpy as np + >>> a = np.array([[1, 2, 4], [1, 4, 0], [1, 0, 4]]) + >>> b = np.array([[4, 2, 0], [4, 4, 0], [4, 0, 2]]) + >>> c = np.array([[3, 2, -1], [1, 2, -1]]) + >>> atol_vectoriser = Atol(quantiser=KMeans(n_clusters=2, random_state=202006)) + >>> atol_vectoriser.fit(X=[a, b, c]).centers + array([[ 2. , 0.66666667, 3.33333333], + [ 2.6 , 2.8 , -0.4 ]]) + >>> atol_vectoriser(a) + array([1.18168665, 0.42375966]) + >>> atol_vectoriser(c) + array([0.02062512, 1.25157463]) + >>> atol_vectoriser.transform(X=[a, b, c]) + array([[1.18168665, 0.42375966], + [0.29861028, 1.06330156], + [0.02062512, 1.25157463]]) + """ + def __init__(self, quantiser, weighting_method="cloud", contrast="gaussian"): + """ + Constructor for the Atol measure vectorisation class. + + Parameters: + quantiser (Object): Object with `fit` (sklearn API consistent) and `cluster_centers` and `n_clusters` + attributes, e.g. sklearn.cluster.KMeans. It will be fitted when the Atol object function `fit` is called. + weighting_method (string): constant generic function for weighting the measure points + choose from {"cloud", "iidproba"} + (default: constant function, i.e. the measure is seen as a point cloud by default). + This will have no impact if weights are provided along with measures all the way: `fit` and `transform`. + contrast (string): constant function for evaluating proximity of a measure with respect to centers + choose from {"gaussian", "laplacian", "indicator"} + (default: gaussian contrast function, see page 3 in the ATOL paper). + """ + self.quantiser = quantiser + self.contrast = { + "gaussian": _gaus_contrast, + "laplacian": _lapl_contrast, + "indicator": _indicator_contrast, + }.get(contrast, _gaus_contrast) + self.weighting_method = { + "cloud" : _cloud_weighting, + "iidproba": _iidproba_weighting, + }.get(weighting_method, _cloud_weighting) + + def fit(self, X, y=None, sample_weight=None): + """ + Calibration step: fit centers to the sample measures and derive inertias between centers. + + Parameters: + X (list N x d numpy arrays): input measures in R^d from which to learn center locations and inertias + (measures can have different N). + y: Ignored, present for API consistency by convention. + sample_weight (list of numpy arrays): weights for each measure point in X, optional. + If None, the object's weighting_method will be used. + + Returns: + self + """ + if not hasattr(self.quantiser, 'fit'): + raise TypeError("quantiser %s has no `fit` attribute." % (self.quantiser)) + if sample_weight is None: + sample_weight = np.concatenate([self.weighting_method(measure) for measure in X]) + + measures_concat = np.concatenate(X) + self.quantiser.fit(X=measures_concat, sample_weight=sample_weight) + self.centers = self.quantiser.cluster_centers_ + if self.quantiser.n_clusters == 1: + dist_centers = pairwise.pairwise_distances(measures_concat) + np.fill_diagonal(dist_centers, 0) + self.inertias = np.array([np.max(dist_centers)/2]) + else: + dist_centers = pairwise.pairwise_distances(self.centers) + dist_centers[dist_centers == 0] = np.inf + self.inertias = np.min(dist_centers, axis=0)/2 + return self + + def __call__(self, measure, sample_weight=None): + """ + Apply measure vectorisation on a single measure. + + Parameters: + measure (n x d numpy array): input measure in R^d. + + Returns: + numpy array in R^self.quantiser.n_clusters. + """ + if sample_weight is None: + sample_weight = self.weighting_method(measure) + return np.sum(sample_weight * self.contrast(measure, self.centers, self.inertias.T).T, axis=1) + + def transform(self, X, sample_weight=None): + """ + Apply measure vectorisation on a list of measures. + + Parameters: + X (list N x d numpy arrays): input measures in R^d from which to learn center locations and inertias + (measures can have different N). + sample_weight (list of numpy arrays): weights for each measure point in X, optional. + If None, the object's weighting_method will be used. + + Returns: + numpy array with shape (number of measures) x (self.quantiser.n_clusters). + """ + if sample_weight is None: + sample_weight = [self.weighting_method(measure) for measure in X] + return np.stack([self(measure, sample_weight=weight) for measure, weight in zip(X, sample_weight)]) |