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diff --git a/.venv/lib/python3.12/site-packages/networkx/algorithms/node_classification.py b/.venv/lib/python3.12/site-packages/networkx/algorithms/node_classification.py new file mode 100644 index 00000000..b69a6c97 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/algorithms/node_classification.py @@ -0,0 +1,219 @@ +"""This module provides the functions for node classification problem. + +The functions in this module are not imported +into the top level `networkx` namespace. +You can access these functions by importing +the `networkx.algorithms.node_classification` modules, +then accessing the functions as attributes of `node_classification`. +For example: + + >>> from networkx.algorithms import node_classification + >>> G = nx.path_graph(4) + >>> G.edges() + EdgeView([(0, 1), (1, 2), (2, 3)]) + >>> G.nodes[0]["label"] = "A" + >>> G.nodes[3]["label"] = "B" + >>> node_classification.harmonic_function(G) + ['A', 'A', 'B', 'B'] + +References +---------- +Zhu, X., Ghahramani, Z., & Lafferty, J. (2003, August). +Semi-supervised learning using gaussian fields and harmonic functions. +In ICML (Vol. 3, pp. 912-919). +""" + +import networkx as nx + +__all__ = ["harmonic_function", "local_and_global_consistency"] + + +@nx.utils.not_implemented_for("directed") +@nx._dispatchable(node_attrs="label_name") +def harmonic_function(G, max_iter=30, label_name="label"): + """Node classification by Harmonic function + + Function for computing Harmonic function algorithm by Zhu et al. + + Parameters + ---------- + G : NetworkX Graph + max_iter : int + maximum number of iterations allowed + label_name : string + name of target labels to predict + + Returns + ------- + predicted : list + List of length ``len(G)`` with the predicted labels for each node. + + Raises + ------ + NetworkXError + If no nodes in `G` have attribute `label_name`. + + Examples + -------- + >>> from networkx.algorithms import node_classification + >>> G = nx.path_graph(4) + >>> G.nodes[0]["label"] = "A" + >>> G.nodes[3]["label"] = "B" + >>> G.nodes(data=True) + NodeDataView({0: {'label': 'A'}, 1: {}, 2: {}, 3: {'label': 'B'}}) + >>> G.edges() + EdgeView([(0, 1), (1, 2), (2, 3)]) + >>> predicted = node_classification.harmonic_function(G) + >>> predicted + ['A', 'A', 'B', 'B'] + + References + ---------- + Zhu, X., Ghahramani, Z., & Lafferty, J. (2003, August). + Semi-supervised learning using gaussian fields and harmonic functions. + In ICML (Vol. 3, pp. 912-919). + """ + import numpy as np + import scipy as sp + + X = nx.to_scipy_sparse_array(G) # adjacency matrix + labels, label_dict = _get_label_info(G, label_name) + + if labels.shape[0] == 0: + raise nx.NetworkXError( + f"No node on the input graph is labeled by '{label_name}'." + ) + + n_samples = X.shape[0] + n_classes = label_dict.shape[0] + F = np.zeros((n_samples, n_classes)) + + # Build propagation matrix + degrees = X.sum(axis=0) + degrees[degrees == 0] = 1 # Avoid division by 0 + # TODO: csr_array + D = sp.sparse.csr_array(sp.sparse.diags((1.0 / degrees), offsets=0)) + P = (D @ X).tolil() + P[labels[:, 0]] = 0 # labels[:, 0] indicates IDs of labeled nodes + # Build base matrix + B = np.zeros((n_samples, n_classes)) + B[labels[:, 0], labels[:, 1]] = 1 + + for _ in range(max_iter): + F = (P @ F) + B + + return label_dict[np.argmax(F, axis=1)].tolist() + + +@nx.utils.not_implemented_for("directed") +@nx._dispatchable(node_attrs="label_name") +def local_and_global_consistency(G, alpha=0.99, max_iter=30, label_name="label"): + """Node classification by Local and Global Consistency + + Function for computing Local and global consistency algorithm by Zhou et al. + + Parameters + ---------- + G : NetworkX Graph + alpha : float + Clamping factor + max_iter : int + Maximum number of iterations allowed + label_name : string + Name of target labels to predict + + Returns + ------- + predicted : list + List of length ``len(G)`` with the predicted labels for each node. + + Raises + ------ + NetworkXError + If no nodes in `G` have attribute `label_name`. + + Examples + -------- + >>> from networkx.algorithms import node_classification + >>> G = nx.path_graph(4) + >>> G.nodes[0]["label"] = "A" + >>> G.nodes[3]["label"] = "B" + >>> G.nodes(data=True) + NodeDataView({0: {'label': 'A'}, 1: {}, 2: {}, 3: {'label': 'B'}}) + >>> G.edges() + EdgeView([(0, 1), (1, 2), (2, 3)]) + >>> predicted = node_classification.local_and_global_consistency(G) + >>> predicted + ['A', 'A', 'B', 'B'] + + References + ---------- + Zhou, D., Bousquet, O., Lal, T. N., Weston, J., & Schölkopf, B. (2004). + Learning with local and global consistency. + Advances in neural information processing systems, 16(16), 321-328. + """ + import numpy as np + import scipy as sp + + X = nx.to_scipy_sparse_array(G) # adjacency matrix + labels, label_dict = _get_label_info(G, label_name) + + if labels.shape[0] == 0: + raise nx.NetworkXError( + f"No node on the input graph is labeled by '{label_name}'." + ) + + n_samples = X.shape[0] + n_classes = label_dict.shape[0] + F = np.zeros((n_samples, n_classes)) + + # Build propagation matrix + degrees = X.sum(axis=0) + degrees[degrees == 0] = 1 # Avoid division by 0 + # TODO: csr_array + D2 = np.sqrt(sp.sparse.csr_array(sp.sparse.diags((1.0 / degrees), offsets=0))) + P = alpha * ((D2 @ X) @ D2) + # Build base matrix + B = np.zeros((n_samples, n_classes)) + B[labels[:, 0], labels[:, 1]] = 1 - alpha + + for _ in range(max_iter): + F = (P @ F) + B + + return label_dict[np.argmax(F, axis=1)].tolist() + + +def _get_label_info(G, label_name): + """Get and return information of labels from the input graph + + Parameters + ---------- + G : Network X graph + label_name : string + Name of the target label + + Returns + ------- + labels : numpy array, shape = [n_labeled_samples, 2] + Array of pairs of labeled node ID and label ID + label_dict : numpy array, shape = [n_classes] + Array of labels + i-th element contains the label corresponding label ID `i` + """ + import numpy as np + + labels = [] + label_to_id = {} + lid = 0 + for i, n in enumerate(G.nodes(data=True)): + if label_name in n[1]: + label = n[1][label_name] + if label not in label_to_id: + label_to_id[label] = lid + lid += 1 + labels.append([i, label_to_id[label]]) + labels = np.array(labels) + label_dict = np.array( + [label for label, _ in sorted(label_to_id.items(), key=lambda x: x[1])] + ) + return (labels, label_dict) |