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Diffstat (limited to 'ot/lp/__init__.py')
| -rw-r--r-- | ot/lp/__init__.py | 602 |
1 files changed, 562 insertions, 40 deletions
diff --git a/ot/lp/__init__.py b/ot/lp/__init__.py index 02cbd8c..cdd505d 100644 --- a/ot/lp/__init__.py +++ b/ot/lp/__init__.py @@ -1,6 +1,9 @@ # -*- coding: utf-8 -*- """ Solvers for the original linear program OT problem + + + """ # Author: Remi Flamary <remi.flamary@unice.fr> @@ -8,22 +11,171 @@ Solvers for the original linear program OT problem # License: MIT License import multiprocessing - +import sys import numpy as np +from scipy.sparse import coo_matrix from .import cvx # import compiled emd -from .emd_wrap import emd_c, check_result +from .emd_wrap import emd_c, check_result, emd_1d_sorted from ..utils import parmap from .cvx import barycenter from ..utils import dist -__all__=['emd', 'emd2', 'barycenter', 'free_support_barycenter', 'cvx'] +__all__ = ['emd', 'emd2', 'barycenter', 'free_support_barycenter', 'cvx', + 'emd_1d', 'emd2_1d', 'wasserstein_1d'] -def emd(a, b, M, numItermax=100000, log=False): - """Solves the Earth Movers distance problem and returns the OT matrix +def center_ot_dual(alpha0, beta0, a=None, b=None): + r"""Center dual OT potentials w.r.t. theirs weights + + The main idea of this function is to find unique dual potentials + that ensure some kind of centering/fairness. The main idea is to find dual potentials that lead to the same final objective value for both source and targets (see below for more details). It will help having + stability when multiple calling of the OT solver with small changes. + + Basically we add another constraint to the potential that will not + change the objective value but will ensure unicity. The constraint + is the following: + + .. math:: + \alpha^T a= \beta^T b + + in addition to the OT problem constraints. + + since :math:`\sum_i a_i=\sum_j b_j` this can be solved by adding/removing + a constant from both :math:`\alpha_0` and :math:`\beta_0`. + + .. math:: + c=\frac{\beta0^T b-\alpha_0^T a}{1^Tb+1^Ta} + + \alpha=\alpha_0+c + + \beta=\beta0+c + + Parameters + ---------- + alpha0 : (ns,) numpy.ndarray, float64 + Source dual potential + beta0 : (nt,) numpy.ndarray, float64 + Target dual potential + a : (ns,) numpy.ndarray, float64 + Source histogram (uniform weight if empty list) + b : (nt,) numpy.ndarray, float64 + Target histogram (uniform weight if empty list) + + Returns + ------- + alpha : (ns,) numpy.ndarray, float64 + Source centered dual potential + beta : (nt,) numpy.ndarray, float64 + Target centered dual potential + + """ + # if no weights are provided, use uniform + if a is None: + a = np.ones(alpha0.shape[0]) / alpha0.shape[0] + if b is None: + b = np.ones(beta0.shape[0]) / beta0.shape[0] + + # compute constant that balances the weighted sums of the duals + c = (b.dot(beta0) - a.dot(alpha0)) / (a.sum() + b.sum()) + + # update duals + alpha = alpha0 + c + beta = beta0 - c + + return alpha, beta + + +def estimate_dual_null_weights(alpha0, beta0, a, b, M): + r"""Estimate feasible values for 0-weighted dual potentials + + The feasible values are computed efficiently but rather coarsely. + + .. warning:: + This function is necessary because the C++ solver in emd_c + discards all samples in the distributions with + zeros weights. This means that while the primal variable (transport + matrix) is exact, the solver only returns feasible dual potentials + on the samples with weights different from zero. + + First we compute the constraints violations: + + .. math:: + V=\alpha+\beta^T-M + + Next we compute the max amount of violation per row (alpha) and + columns (beta) + + .. math:: + v^a_i=\max_j V_{i,j} + + v^b_j=\max_i V_{i,j} + + Finally we update the dual potential with 0 weights if a + constraint is violated + + .. math:: + \alpha_i = \alpha_i -v^a_i \quad \text{ if } a_i=0 \text{ and } v^a_i>0 + + \beta_j = \beta_j -v^b_j \quad \text{ if } b_j=0 \text{ and } v^b_j>0 + + In the end the dual potentials are centered using function + :ref:`center_ot_dual`. + + Note that all those updates do not change the objective value of the + solution but provide dual potentials that do not violate the constraints. + + Parameters + ---------- + alpha0 : (ns,) numpy.ndarray, float64 + Source dual potential + beta0 : (nt,) numpy.ndarray, float64 + Target dual potential + alpha0 : (ns,) numpy.ndarray, float64 + Source dual potential + beta0 : (nt,) numpy.ndarray, float64 + Target dual potential + a : (ns,) numpy.ndarray, float64 + Source distribution (uniform weights if empty list) + b : (nt,) numpy.ndarray, float64 + Target distribution (uniform weights if empty list) + M : (ns,nt) numpy.ndarray, float64 + Loss matrix (c-order array with type float64) + + Returns + ------- + alpha : (ns,) numpy.ndarray, float64 + Source corrected dual potential + beta : (nt,) numpy.ndarray, float64 + Target corrected dual potential + + """ + + # binary indexing of non-zeros weights + asel = a != 0 + bsel = b != 0 + + # compute dual constraints violation + constraint_violation = alpha0[:, None] + beta0[None, :] - M + + # Compute largest violation per line and columns + aviol = np.max(constraint_violation, 1) + bviol = np.max(constraint_violation, 0) + + # update corrects violation of + alpha_up = -1 * ~asel * np.maximum(aviol, 0) + beta_up = -1 * ~bsel * np.maximum(bviol, 0) + + alpha = alpha0 + alpha_up + beta = beta0 + beta_up + + return center_ot_dual(alpha, beta, a, b) + + +def emd(a, b, M, numItermax=100000, log=False, dense=True, center_dual=True): + r"""Solves the Earth Movers distance problem and returns the OT matrix .. math:: @@ -37,26 +189,37 @@ def emd(a, b, M, numItermax=100000, log=False): - M is the metric cost matrix - a and b are the sample weights + .. warning:: + Note that the M matrix needs to be a C-order numpy.array in float64 + format. + Uses the algorithm proposed in [1]_ Parameters ---------- - a : (ns,) ndarray, float64 - Source histogram (uniform weigth if empty list) - b : (nt,) ndarray, float64 - Target histogram (uniform weigth if empty list) - M : (ns,nt) ndarray, float64 - loss matrix + a : (ns,) numpy.ndarray, float64 + Source histogram (uniform weight if empty list) + b : (nt,) numpy.ndarray, float64 + Target histogram (uniform weight if empty list) + M : (ns,nt) numpy.ndarray, float64 + Loss matrix (c-order array with type float64) numItermax : int, optional (default=100000) The maximum number of iterations before stopping the optimization algorithm if it has not converged. - log: boolean, optional (default=False) + log: bool, optional (default=False) If True, returns a dictionary containing the cost and dual variables. Otherwise returns only the optimal transportation matrix. + dense: boolean, optional (default=True) + If True, returns math:`\gamma` as a dense ndarray of shape (ns, nt). + Otherwise returns a sparse representation using scipy's `coo_matrix` + format. + center_dual: boolean, optional (default=True) + If True, centers the dual potential using function + :ref:`center_ot_dual`. Returns ------- - gamma: (ns x nt) ndarray + gamma: (ns x nt) numpy.ndarray Optimal transportation matrix for the given parameters log: dict If input log is true, a dictionary containing the cost and dual @@ -74,8 +237,8 @@ def emd(a, b, M, numItermax=100000, log=False): >>> b=[.5,.5] >>> M=[[0.,1.],[1.,0.]] >>> ot.emd(a,b,M) - array([[ 0.5, 0. ], - [ 0. , 0.5]]) + array([[0.5, 0. ], + [0. , 0.5]]) References ---------- @@ -94,13 +257,37 @@ def emd(a, b, M, numItermax=100000, log=False): b = np.asarray(b, dtype=np.float64) M = np.asarray(M, dtype=np.float64) - # if empty array given then use unifor distributions + # if empty array given then use uniform distributions if len(a) == 0: a = np.ones((M.shape[0],), dtype=np.float64) / M.shape[0] if len(b) == 0: b = np.ones((M.shape[1],), dtype=np.float64) / M.shape[1] - G, cost, u, v, result_code = emd_c(a, b, M, numItermax) + assert (a.shape[0] == M.shape[0] and b.shape[0] == M.shape[1]), \ + "Dimension mismatch, check dimensions of M with a and b" + + asel = a != 0 + bsel = b != 0 + + if dense: + G, cost, u, v, result_code = emd_c(a, b, M, numItermax, dense) + + if center_dual: + u, v = center_ot_dual(u, v, a, b) + + if np.any(~asel) or np.any(~bsel): + u, v = estimate_dual_null_weights(u, v, a, b, M) + + else: + Gv, iG, jG, cost, u, v, result_code = emd_c(a, b, M, numItermax, dense) + G = coo_matrix((Gv, (iG, jG)), shape=(a.shape[0], b.shape[0])) + + if center_dual: + u, v = center_ot_dual(u, v, a, b) + + if np.any(~asel) or np.any(~bsel): + u, v = estimate_dual_null_weights(u, v, a, b, M) + result_code_string = check_result(result_code) if log: log = {} @@ -114,8 +301,9 @@ def emd(a, b, M, numItermax=100000, log=False): def emd2(a, b, M, processes=multiprocessing.cpu_count(), - numItermax=100000, log=False, return_matrix=False): - """Solves the Earth Movers distance problem and returns the loss + numItermax=100000, log=False, dense=True, return_matrix=False, + center_dual=True): + r"""Solves the Earth Movers distance problem and returns the loss .. math:: \gamma = arg\min_\gamma <\gamma,M>_F @@ -128,16 +316,22 @@ def emd2(a, b, M, processes=multiprocessing.cpu_count(), - M is the metric cost matrix - a and b are the sample weights + .. warning:: + Note that the M matrix needs to be a C-order numpy.array in float64 + format. + Uses the algorithm proposed in [1]_ Parameters ---------- - a : (ns,) ndarray, float64 - Source histogram (uniform weigth if empty list) - b : (nt,) ndarray, float64 - Target histogram (uniform weigth if empty list) - M : (ns,nt) ndarray, float64 - loss matrix + a : (ns,) numpy.ndarray, float64 + Source histogram (uniform weight if empty list) + b : (nt,) numpy.ndarray, float64 + Target histogram (uniform weight if empty list) + M : (ns,nt) numpy.ndarray, float64 + Loss matrix (c-order array with type float64) + processes : int, optional (default=nb cpu) + Nb of processes used for multiple emd computation (not used on windows) numItermax : int, optional (default=100000) The maximum number of iterations before stopping the optimization algorithm if it has not converged. @@ -146,12 +340,19 @@ def emd2(a, b, M, processes=multiprocessing.cpu_count(), variables. Otherwise returns only the optimal transportation cost. return_matrix: boolean, optional (default=False) If True, returns the optimal transportation matrix in the log. + dense: boolean, optional (default=True) + If True, returns math:`\gamma` as a dense ndarray of shape (ns, nt). + Otherwise returns a sparse representation using scipy's `coo_matrix` + format. + center_dual: boolean, optional (default=True) + If True, centers the dual potential using function + :ref:`center_ot_dual`. Returns ------- gamma: (ns x nt) ndarray Optimal transportation matrix for the given parameters - log: dict + log: dictnp If input log is true, a dictionary containing the cost and dual variables and exit status @@ -187,27 +388,61 @@ def emd2(a, b, M, processes=multiprocessing.cpu_count(), b = np.asarray(b, dtype=np.float64) M = np.asarray(M, dtype=np.float64) - # if empty array given then use unifor distributions + # problem with pikling Forks + if sys.platform.endswith('win32'): + processes = 1 + + # if empty array given then use uniform distributions if len(a) == 0: a = np.ones((M.shape[0],), dtype=np.float64) / M.shape[0] if len(b) == 0: b = np.ones((M.shape[1],), dtype=np.float64) / M.shape[1] + assert (a.shape[0] == M.shape[0] and b.shape[0] == M.shape[1]), \ + "Dimension mismatch, check dimensions of M with a and b" + + asel = a != 0 + if log or return_matrix: def f(b): - G, cost, u, v, resultCode = emd_c(a, b, M, numItermax) - result_code_string = check_result(resultCode) + bsel = b != 0 + if dense: + G, cost, u, v, result_code = emd_c(a, b, M, numItermax, dense) + else: + Gv, iG, jG, cost, u, v, result_code = emd_c(a, b, M, numItermax, dense) + G = coo_matrix((Gv, (iG, jG)), shape=(a.shape[0], b.shape[0])) + + if center_dual: + u, v = center_ot_dual(u, v, a, b) + + if np.any(~asel) or np.any(~bsel): + u, v = estimate_dual_null_weights(u, v, a, b, M) + + result_code_string = check_result(result_code) log = {} if return_matrix: log['G'] = G log['u'] = u log['v'] = v log['warning'] = result_code_string - log['result_code'] = resultCode + log['result_code'] = result_code return [cost, log] else: def f(b): - G, cost, u, v, result_code = emd_c(a, b, M, numItermax) + bsel = b != 0 + if dense: + G, cost, u, v, result_code = emd_c(a, b, M, numItermax, dense) + else: + Gv, iG, jG, cost, u, v, result_code = emd_c(a, b, M, numItermax, dense) + G = coo_matrix((Gv, (iG, jG)), shape=(a.shape[0], b.shape[0])) + + if center_dual: + u, v = center_ot_dual(u, v, a, b) + + if np.any(~asel) or np.any(~bsel): + u, v = estimate_dual_null_weights(u, v, a, b, M) + + result_code_string = check_result(result_code) check_result(result_code) return cost @@ -215,9 +450,12 @@ def emd2(a, b, M, processes=multiprocessing.cpu_count(), return f(b) nb = b.shape[1] - res = parmap(f, [b[:, i] for i in range(nb)], processes) - return res + if processes > 1: + res = parmap(f, [b[:, i] for i in range(nb)], processes) + else: + res = list(map(f, [b[:, i].copy() for i in range(nb)])) + return res def free_support_barycenter(measures_locations, measures_weights, X_init, b=None, weights=None, numItermax=100, stopThr=1e-7, verbose=False, log=None): @@ -231,9 +469,9 @@ def free_support_barycenter(measures_locations, measures_weights, X_init, b=None Parameters ---------- - measures_locations : list of (k_i,d) np.ndarray + measures_locations : list of (k_i,d) numpy.ndarray The discrete support of a measure supported on k_i locations of a d-dimensional space (k_i can be different for each element of the list) - measures_weights : list of (k_i,) np.ndarray + measures_weights : list of (k_i,) numpy.ndarray Numpy arrays where each numpy array has k_i non-negatives values summing to one representing the weights of each discrete input measure X_init : (k,d) np.ndarray @@ -246,7 +484,7 @@ def free_support_barycenter(measures_locations, measures_weights, X_init, b=None numItermax : int, optional Max number of iterations stopThr : float, optional - Stop threshol on error (>0) + Stop threshold on error (>0) verbose : bool, optional Print information along iterations log : bool, optional @@ -272,7 +510,7 @@ def free_support_barycenter(measures_locations, measures_weights, X_init, b=None k = X_init.shape[0] d = X_init.shape[1] if b is None: - b = np.ones((k,))/k + b = np.ones((k,)) / k if weights is None: weights = np.ones((N,)) / N @@ -283,7 +521,7 @@ def free_support_barycenter(measures_locations, measures_weights, X_init, b=None displacement_square_norm = stopThr + 1. - while ( displacement_square_norm > stopThr and iter_count < numItermax ): + while (displacement_square_norm > stopThr and iter_count < numItermax): T_sum = np.zeros((k, d)) @@ -293,7 +531,7 @@ def free_support_barycenter(measures_locations, measures_weights, X_init, b=None T_i = emd(b, measure_weights_i, M_i) T_sum = T_sum + weight_i * np.reshape(1. / b, (-1, 1)) * np.matmul(T_i, measure_locations_i) - displacement_square_norm = np.sum(np.square(T_sum-X)) + displacement_square_norm = np.sum(np.square(T_sum - X)) if log: displacement_square_norms.append(displacement_square_norm) @@ -308,4 +546,288 @@ def free_support_barycenter(measures_locations, measures_weights, X_init, b=None log_dict['displacement_square_norms'] = displacement_square_norms return X, log_dict else: - return X
\ No newline at end of file + return X + + +def emd_1d(x_a, x_b, a=None, b=None, metric='sqeuclidean', p=1., dense=True, + log=False): + r"""Solves the Earth Movers distance problem between 1d measures and returns + the OT matrix + + + .. math:: + \gamma = arg\min_\gamma \sum_i \sum_j \gamma_{ij} d(x_a[i], x_b[j]) + + s.t. \gamma 1 = a, + \gamma^T 1= b, + \gamma\geq 0 + where : + + - d is the metric + - x_a and x_b are the samples + - a and b are the sample weights + + When 'minkowski' is used as a metric, :math:`d(x, y) = |x - y|^p`. + + Uses the algorithm detailed in [1]_ + + Parameters + ---------- + x_a : (ns,) or (ns, 1) ndarray, float64 + Source dirac locations (on the real line) + x_b : (nt,) or (ns, 1) ndarray, float64 + Target dirac locations (on the real line) + a : (ns,) ndarray, float64, optional + Source histogram (default is uniform weight) + b : (nt,) ndarray, float64, optional + Target histogram (default is uniform weight) + metric: str, optional (default='sqeuclidean') + Metric to be used. Only strings listed in :func:`ot.dist` are accepted. + Due to implementation details, this function runs faster when + `'sqeuclidean'`, `'cityblock'`, or `'euclidean'` metrics are used. + p: float, optional (default=1.0) + The p-norm to apply for if metric='minkowski' + dense: boolean, optional (default=True) + If True, returns math:`\gamma` as a dense ndarray of shape (ns, nt). + Otherwise returns a sparse representation using scipy's `coo_matrix` + format. Due to implementation details, this function runs faster when + `'sqeuclidean'`, `'minkowski'`, `'cityblock'`, or `'euclidean'` metrics + are used. + log: boolean, optional (default=False) + If True, returns a dictionary containing the cost. + Otherwise returns only the optimal transportation matrix. + + Returns + ------- + gamma: (ns, nt) ndarray + Optimal transportation matrix for the given parameters + log: dict + If input log is True, a dictionary containing the cost + + + Examples + -------- + + Simple example with obvious solution. The function emd_1d accepts lists and + performs automatic conversion to numpy arrays + + >>> import ot + >>> a=[.5, .5] + >>> b=[.5, .5] + >>> x_a = [2., 0.] + >>> x_b = [0., 3.] + >>> ot.emd_1d(x_a, x_b, a, b) + array([[0. , 0.5], + [0.5, 0. ]]) + >>> ot.emd_1d(x_a, x_b) + array([[0. , 0.5], + [0.5, 0. ]]) + + References + ---------- + + .. [1] Peyré, G., & Cuturi, M. (2017). "Computational Optimal + Transport", 2018. + + See Also + -------- + ot.lp.emd : EMD for multidimensional distributions + ot.lp.emd2_1d : EMD for 1d distributions (returns cost instead of the + transportation matrix) + """ + a = np.asarray(a, dtype=np.float64) + b = np.asarray(b, dtype=np.float64) + x_a = np.asarray(x_a, dtype=np.float64) + x_b = np.asarray(x_b, dtype=np.float64) + + assert (x_a.ndim == 1 or x_a.ndim == 2 and x_a.shape[1] == 1), \ + "emd_1d should only be used with monodimensional data" + assert (x_b.ndim == 1 or x_b.ndim == 2 and x_b.shape[1] == 1), \ + "emd_1d should only be used with monodimensional data" + + # if empty array given then use uniform distributions + if a.ndim == 0 or len(a) == 0: + a = np.ones((x_a.shape[0],), dtype=np.float64) / x_a.shape[0] + if b.ndim == 0 or len(b) == 0: + b = np.ones((x_b.shape[0],), dtype=np.float64) / x_b.shape[0] + + x_a_1d = x_a.reshape((-1, )) + x_b_1d = x_b.reshape((-1, )) + perm_a = np.argsort(x_a_1d) + perm_b = np.argsort(x_b_1d) + + G_sorted, indices, cost = emd_1d_sorted(a, b, + x_a_1d[perm_a], x_b_1d[perm_b], + metric=metric, p=p) + G = coo_matrix((G_sorted, (perm_a[indices[:, 0]], perm_b[indices[:, 1]])), + shape=(a.shape[0], b.shape[0])) + if dense: + G = G.toarray() + if log: + log = {'cost': cost} + return G, log + return G + + +def emd2_1d(x_a, x_b, a=None, b=None, metric='sqeuclidean', p=1., dense=True, + log=False): + r"""Solves the Earth Movers distance problem between 1d measures and returns + the loss + + + .. math:: + \gamma = arg\min_\gamma \sum_i \sum_j \gamma_{ij} d(x_a[i], x_b[j]) + + s.t. \gamma 1 = a, + \gamma^T 1= b, + \gamma\geq 0 + where : + + - d is the metric + - x_a and x_b are the samples + - a and b are the sample weights + + When 'minkowski' is used as a metric, :math:`d(x, y) = |x - y|^p`. + + Uses the algorithm detailed in [1]_ + + Parameters + ---------- + x_a : (ns,) or (ns, 1) ndarray, float64 + Source dirac locations (on the real line) + x_b : (nt,) or (ns, 1) ndarray, float64 + Target dirac locations (on the real line) + a : (ns,) ndarray, float64, optional + Source histogram (default is uniform weight) + b : (nt,) ndarray, float64, optional + Target histogram (default is uniform weight) + metric: str, optional (default='sqeuclidean') + Metric to be used. Only strings listed in :func:`ot.dist` are accepted. + Due to implementation details, this function runs faster when + `'sqeuclidean'`, `'minkowski'`, `'cityblock'`, or `'euclidean'` metrics + are used. + p: float, optional (default=1.0) + The p-norm to apply for if metric='minkowski' + dense: boolean, optional (default=True) + If True, returns math:`\gamma` as a dense ndarray of shape (ns, nt). + Otherwise returns a sparse representation using scipy's `coo_matrix` + format. Only used if log is set to True. Due to implementation details, + this function runs faster when dense is set to False. + log: boolean, optional (default=False) + If True, returns a dictionary containing the transportation matrix. + Otherwise returns only the loss. + + Returns + ------- + loss: float + Cost associated to the optimal transportation + log: dict + If input log is True, a dictionary containing the Optimal transportation + matrix for the given parameters + + + Examples + -------- + + Simple example with obvious solution. The function emd2_1d accepts lists and + performs automatic conversion to numpy arrays + + >>> import ot + >>> a=[.5, .5] + >>> b=[.5, .5] + >>> x_a = [2., 0.] + >>> x_b = [0., 3.] + >>> ot.emd2_1d(x_a, x_b, a, b) + 0.5 + >>> ot.emd2_1d(x_a, x_b) + 0.5 + + References + ---------- + + .. [1] Peyré, G., & Cuturi, M. (2017). "Computational Optimal + Transport", 2018. + + See Also + -------- + ot.lp.emd2 : EMD for multidimensional distributions + ot.lp.emd_1d : EMD for 1d distributions (returns the transportation matrix + instead of the cost) + """ + # If we do not return G (log==False), then we should not to cast it to dense + # (useless overhead) + G, log_emd = emd_1d(x_a=x_a, x_b=x_b, a=a, b=b, metric=metric, p=p, + dense=dense and log, log=True) + cost = log_emd['cost'] + if log: + log_emd = {'G': G} + return cost, log_emd + return cost + + +def wasserstein_1d(x_a, x_b, a=None, b=None, p=1.): + r"""Solves the p-Wasserstein distance problem between 1d measures and returns + the distance + + .. math:: + \min_\gamma \left( \sum_i \sum_j \gamma_{ij} \|x_a[i] - x_b[j]\|^p \right)^{1/p} + + s.t. \gamma 1 = a, + \gamma^T 1= b, + \gamma\geq 0 + + where : + + - x_a and x_b are the samples + - a and b are the sample weights + + Uses the algorithm detailed in [1]_ + + Parameters + ---------- + x_a : (ns,) or (ns, 1) ndarray, float64 + Source dirac locations (on the real line) + x_b : (nt,) or (ns, 1) ndarray, float64 + Target dirac locations (on the real line) + a : (ns,) ndarray, float64, optional + Source histogram (default is uniform weight) + b : (nt,) ndarray, float64, optional + Target histogram (default is uniform weight) + p: float, optional (default=1.0) + The order of the p-Wasserstein distance to be computed + + Returns + ------- + dist: float + p-Wasserstein distance + + + Examples + -------- + + Simple example with obvious solution. The function wasserstein_1d accepts + lists and performs automatic conversion to numpy arrays + + >>> import ot + >>> a=[.5, .5] + >>> b=[.5, .5] + >>> x_a = [2., 0.] + >>> x_b = [0., 3.] + >>> ot.wasserstein_1d(x_a, x_b, a, b) + 0.5 + >>> ot.wasserstein_1d(x_a, x_b) + 0.5 + + References + ---------- + + .. [1] Peyré, G., & Cuturi, M. (2017). "Computational Optimal + Transport", 2018. + + See Also + -------- + ot.lp.emd_1d : EMD for 1d distributions + """ + cost_emd = emd2_1d(x_a=x_a, x_b=x_b, a=a, b=b, metric='minkowski', p=p, + dense=False, log=False) + return np.power(cost_emd, 1. / p) |