utils.py

import numpy as np
import networkx as nx
import scipy.sparse as sp
import torch
import scipy.io as sio
import random
import dgl


def sparse_to_tuple(sparse_mx, insert_batch=False):
    """Convert sparse matrix to tuple representation."""
    """Set insert_batch=True if you want to insert a batch dimension."""
    def to_tuple(mx):
        if not sp.isspmatrix_coo(mx):
            mx = mx.tocoo()
        if insert_batch:
            coords = np.vstack((np.zeros(mx.row.shape[0]), mx.row, mx.col)).transpose()
            values = mx.data
            shape = (1,) + mx.shape
        else:
            coords = np.vstack((mx.row, mx.col)).transpose()
            values = mx.data
            shape = mx.shape
        return coords, values, shape

    if isinstance(sparse_mx, list):
        for i in range(len(sparse_mx)):
            sparse_mx[i] = to_tuple(sparse_mx[i])
    else:
        sparse_mx = to_tuple(sparse_mx)

    return sparse_mx

def preprocess_features(features):
    """Row-normalize feature matrix and convert to tuple representation"""
    rowsum = np.array(features.sum(1))
    r_inv = np.power(rowsum, -1).flatten()
    r_inv[np.isinf(r_inv)] = 0.
    r_mat_inv = sp.diags(r_inv)
    features = r_mat_inv.dot(features)
    return features.todense(), sparse_to_tuple(features)

def normalize_adj(adj):
    """Symmetrically normalize adjacency matrix."""
    adj = sp.coo_matrix(adj)
    rowsum = np.array(adj.sum(1))
    d_inv_sqrt = np.power(rowsum, -0.5).flatten()
    d_inv_sqrt[np.isinf(d_inv_sqrt)] = 0.
    d_mat_inv_sqrt = sp.diags(d_inv_sqrt)
    return adj.dot(d_mat_inv_sqrt).transpose().dot(d_mat_inv_sqrt).tocoo()

def dense_to_one_hot(labels_dense, num_classes):
    """Convert class labels from scalars to one-hot vectors."""
    num_labels = labels_dense.shape[0]
    index_offset = np.arange(num_labels) * num_classes
    labels_one_hot = np.zeros((num_labels, num_classes))
    labels_one_hot.flat[index_offset+labels_dense.ravel()] = 1
    return labels_one_hot

def load_mat(dataset, train_rate=0.3, val_rate=0.1):
    """Load .mat dataset."""
    data = sio.loadmat("./dataset/{}.mat".format(dataset))
    label = data['Label'] if ('Label' in data) else data['gnd']
    attr = data['Attributes'] if ('Attributes' in data) else data['X']
    network = data['Network'] if ('Network' in data) else data['A']

    adj = sp.csr_matrix(network)
    feat = sp.lil_matrix(attr)

    labels = np.squeeze(np.array(data['Class'],dtype=np.int64) - 1)
    num_classes = np.max(labels) + 1
    labels = dense_to_one_hot(labels,num_classes)

    ano_labels = np.squeeze(np.array(label))
    if 'str_anomaly_label' in data:
        str_ano_labels = np.squeeze(np.array(data['str_anomaly_label']))
        attr_ano_labels = np.squeeze(np.array(data['attr_anomaly_label']))
    else:
        str_ano_labels = None
        attr_ano_labels = None

    num_node = adj.shape[0]
    num_train = int(num_node * train_rate)
    num_val = int(num_node * val_rate)
    all_idx = list(range(num_node))
    random.shuffle(all_idx)
    idx_train = all_idx[ : num_train]
    idx_val = all_idx[num_train : num_train + num_val]
    idx_test = all_idx[num_train + num_val : ]

    return adj, feat, labels, idx_train, idx_val, idx_test, ano_labels, str_ano_labels, attr_ano_labels

def adj_to_dgl_graph(adj):
    """Convert adjacency matrix to dgl format."""
    nx_graph = nx.from_scipy_sparse_matrix(adj)
    dgl_graph = dgl.DGLGraph(nx_graph)
    return dgl_graph

def generate_rwr_subgraph(dgl_graph, subgraph_size):
    """Generate subgraph with RWR algorithm."""
    all_idx = list(range(dgl_graph.number_of_nodes()))
    reduced_size = subgraph_size - 1
    traces = dgl.contrib.sampling.random_walk_with_restart(dgl_graph, all_idx, restart_prob=1, max_nodes_per_seed=subgraph_size*3)
    subv = []

    for i,trace in enumerate(traces):
        subv.append(torch.unique(torch.cat(trace),sorted=False).tolist())
        retry_time = 0
        while len(subv[i]) < reduced_size:
            cur_trace = dgl.contrib.sampling.random_walk_with_restart(dgl_graph, [i], restart_prob=0.9, max_nodes_per_seed=subgraph_size*5)
            subv[i] = torch.unique(torch.cat(cur_trace[0]),sorted=False).tolist()
            retry_time += 1
            if (len(subv[i]) <= 2) and (retry_time >10):
                subv[i] = (subv[i] * reduced_size)
        subv[i] = subv[i][:reduced_size]
        subv[i].append(i)

    return subv