utils.py

import torch
from torch_geometric.utils import to_networkx, degree, to_scipy_sparse_matrix
import torch.nn.functional as F
from sklearn.model_selection import train_test_split
from scipy import sparse as sp

def convert_to_nodeDegreeFeatures(graphs):
    graph_infos = []
    maxdegree = 0
    for i, graph in enumerate(graphs):
        g = to_networkx(graph, to_undirected=True)
        gdegree = max(dict(g.degree).values())
        if gdegree > maxdegree:
            maxdegree = gdegree
        graph_infos.append((graph, g.degree, graph.num_nodes)) 

    new_graphs = []
    for i, tuple in enumerate(graph_infos):
        idx, x = tuple[0].edge_index[0], tuple[0].x
        deg = degree(idx, tuple[2], dtype=torch.long)
        deg = F.one_hot(deg, num_classes=maxdegree + 1).to(torch.float)

        new_graph = tuple[0].clone()
        new_graph.__setitem__('x', deg)
        new_graphs.append(new_graph)

    return new_graphs

def get_maxDegree(graphs):
    maxdegree = 0
    for i, graph in enumerate(graphs):
        g = to_networkx(graph, to_undirected=True)
        gdegree = max(dict(g.degree).values())
        if gdegree > maxdegree:
            maxdegree = gdegree

    return maxdegree

def split_data(graphs, train=None, test=None, shuffle=True, seed=None):
    y = torch.cat([graph.y for graph in graphs])
    graphs_tv, graphs_test = train_test_split(graphs, train_size=train, test_size=test, stratify=y, shuffle=shuffle, random_state=seed)
    return graphs_tv, graphs_test


def get_numGraphLabels(dataset):
    s = set()
    for g in dataset:
        s.add(g.y.item())
    return len(s)


def _get_avg_nodes_edges(graphs):
    numNodes = 0.
    numEdges = 0.
    numGraphs = len(graphs)
    for g in graphs:
        numNodes += g.num_nodes
        numEdges += g.num_edges / 2.  # undirected
    return numNodes/numGraphs, numEdges/numGraphs


def get_stats(df, ds, graphs_train, graphs_val=None, graphs_test=None):
    df.loc[ds, "#graphs_train"] = len(graphs_train)
    avgNodes, avgEdges = _get_avg_nodes_edges(graphs_train)
    df.loc[ds, 'avgNodes_train'] = avgNodes
    df.loc[ds, 'avgEdges_train'] = avgEdges

    if graphs_val:
        df.loc[ds, '#graphs_val'] = len(graphs_val)
        avgNodes, avgEdges = _get_avg_nodes_edges(graphs_val)
        df.loc[ds, 'avgNodes_val'] = avgNodes
        df.loc[ds, 'avgEdges_val'] = avgEdges

    if graphs_test:
        df.loc[ds, '#graphs_test'] = len(graphs_test)
        avgNodes, avgEdges = _get_avg_nodes_edges(graphs_test)
        df.loc[ds, 'avgNodes_test'] = avgNodes
        df.loc[ds, 'avgEdges_test'] = avgEdges

    return df

def init_structure_encoding(args, gs, type_init):

    if type_init == 'rw':
        for g in gs:
            A = to_scipy_sparse_matrix(g.edge_index, num_nodes=g.num_nodes)
            D = (degree(g.edge_index[0], num_nodes=g.num_nodes) ** -1.0).numpy()

            Dinv=sp.diags(D)
            RW=A*Dinv
            M=RW

            SE_rw=[torch.from_numpy(M.diagonal()).float()]
            M_power=M
            for _ in range(args.n_rw-1):
                M_power=M_power*M
                SE_rw.append(torch.from_numpy(M_power.diagonal()).float())
            SE_rw=torch.stack(SE_rw,dim=-1)

            g['stc_enc'] = SE_rw

    elif type_init == 'dg':
        for g in gs:
            # PE_degree
            g_dg = (degree(g.edge_index[0], num_nodes=g.num_nodes)).numpy().clip(1, args.n_dg)
            SE_dg = torch.zeros([g.num_nodes, args.n_dg])
            for i in range(len(g_dg)):
                SE_dg[i,int(g_dg[i]-1)] = 1

            g['stc_enc'] = SE_dg

    elif type_init == 'rw_dg':
        for g in gs:
            # SE_rw
            A = to_scipy_sparse_matrix(g.edge_index, num_nodes=g.num_nodes)
            D = (degree(g.edge_index[0], num_nodes=g.num_nodes) ** -1.0).numpy()

            Dinv=sp.diags(D)
            RW=A*Dinv
            M=RW

            SE=[torch.from_numpy(M.diagonal()).float()]
            M_power=M
            for _ in range(args.n_rw-1):
                M_power=M_power*M
                SE.append(torch.from_numpy(M_power.diagonal()).float())
            SE_rw=torch.stack(SE,dim=-1)

            # PE_degree
            g_dg = (degree(g.edge_index[0], num_nodes=g.num_nodes)).numpy().clip(1, args.n_dg)
            SE_dg = torch.zeros([g.num_nodes, args.n_dg])
            for i in range(len(g_dg)):
                SE_dg[i,int(g_dg[i]-1)] = 1

            g['stc_enc'] = torch.cat([SE_rw, SE_dg], dim=1)

    return gs