U 3d@s@dZddlZddlmZddlmZddddZd d d ZdS)zy Graph utilities and algorithms Graphs are represented with their adjacency matrices, preferably using sparse matrices. N)sparse)pairwise_distances)cutoffcCst|r|}n t|}i}d}|g}|r|}t}|D]$}||kr>|||<||j|q>|dk rv||krvq|d7}q,|S)aAReturn the length of the shortest path from source to all reachable nodes. Parameters ---------- graph : {sparse matrix, ndarray} of shape (n_nodes, n_nodes) Adjacency matrix of the graph. Sparse matrix of format LIL is preferred. source : int Start node for path. cutoff : int, default=None Depth to stop the search - only paths of length <= cutoff are returned. Returns ------- paths : dict Reachable end nodes mapped to length of path from source, i.e. `{end: path_length}`. Examples -------- >>> from sklearn.utils.graph import single_source_shortest_path_length >>> import numpy as np >>> graph = np.array([[ 0, 1, 0, 0], ... [ 1, 0, 1, 0], ... [ 0, 1, 0, 0], ... [ 0, 0, 0, 0]]) >>> single_source_shortest_path_length(graph, 0) {0: 0, 1: 1, 2: 2} >>> graph = np.ones((6, 6)) >>> sorted(single_source_shortest_path_length(graph, 2).items()) [(0, 1), (1, 1), (2, 0), (3, 1), (4, 1), (5, 1)] rN)rZ isspmatrixZtolilZ lil_matrixsetupdateZrows)graphsourcerseenlevelZ next_levelZ this_levelvr7/tmp/pip-unpacked-wheel-zrfo1fqw/sklearn/utils/graph.py"single_source_shortest_path_lengths"#    rdistance euclideancKs4|dkrt|rtdt|D] }t||k}||} t|D]} t|| k} || } |dkrz|t|| } nt| | fd|i|} t| j dd| j \}}|dkrd|||| |f<d|| |||f<qF|dkr | ||f|||| |f<| ||f|| |||f<qFt d |qFq"|S) aAdd connections to sparse graph to connect unconnected components. For each pair of unconnected components, compute all pairwise distances from one component to the other, and add a connection on the closest pair of samples. This is a hacky way to get a graph with a single connected component, which is necessary for example to compute a shortest path between all pairs of samples in the graph. Parameters ---------- X : array of shape (n_samples, n_features) or (n_samples, n_samples) Features to compute the pairwise distances. If `metric = "precomputed"`, X is the matrix of pairwise distances. graph : sparse matrix of shape (n_samples, n_samples) Graph of connection between samples. n_connected_components : int Number of connected components, as computed by `scipy.sparse.csgraph.connected_components`. component_labels : array of shape (n_samples) Labels of connected components, as computed by `scipy.sparse.csgraph.connected_components`. mode : {'connectivity', 'distance'}, default='distance' Type of graph matrix: 'connectivity' corresponds to the connectivity matrix with ones and zeros, and 'distance' corresponds to the distances between neighbors according to the given metric. metric : str Metric used in `sklearn.metrics.pairwise.pairwise_distances`. kwargs : kwargs Keyword arguments passed to `sklearn.metrics.pairwise.pairwise_distances`. Returns ------- graph : sparse matrix of shape (n_samples, n_samples) Graph of connection between samples, with a single connected component. Z precomputedz_fix_connected_components with metric='precomputed' requires the full distance matrix in X, and does not work with a sparse neighbors graph.metricN)ZaxisZ connectivityrrz?Unknown mode=%r, should be one of ['connectivity', 'distance'].) rissparse RuntimeErrorrangenpZ flatnonzeroZix_rZ unravel_indexZargminshape ValueError)Xr Zn_connected_componentsZcomponent_labelsmoderkwargsiZidx_iXijZidx_jZXjDiiZjjrrr_fix_connected_componentsMs43  r")rr) __doc__ZnumpyrZscipyrZmetrics.pairwiserrr"rrrrs   <