C++ igraph教程：从数据文件构建图并设置边权重和节点名称

本教程将指导您使用C++ igraph库从数据文件构建图。我们将涵盖以下内容：

• 读取包含节点和边信息的数据文件。* 将数据的第一列和第二列分别作为边的source和target。* 创建一个igraph图对象。* 为边设置权重。* 为节点设置名称。* 将图保存到GraphML文件。

代码

以下是完整的C++代码：c++#include <igraph/igraph.h>#include #include #include #include <unordered_map>#include

int main() { std::ifstream file('matrix.txt'); std::string line;

std::vector<int> edges;    std::vector<double> weights;    std::vector<std::string> node_names;

std::unordered_map<std::string, int> node_map;    int node_count = 0;

while (std::getline(file, line)) {        std::istringstream iss(line);        std::string u, v;        double w;

    if (!(iss >> u >> v >> w)) {            break;  // error        }

    if (node_map.find(u) == node_map.end()) {            node_map[u] = node_count;            node_names.push_back(u);            node_count++;        }

    if (node_map.find(v) == node_map.end()) {            node_map[v] = node_count;            node_names.push_back(v);            node_count++;        }

    edges.push_back(node_map[u]);        edges.push_back(node_map[v]);        weights.push_back(w);    }

igraph_t graph;    igraph_set_attribute_table(&igraph_cattribute_table);    igraph_empty(&graph, node_count, IGRAPH_UNDIRECTED); // 指定顶点数

igraph_vector_int_t edge_vector;    igraph_vector_int_init(&edge_vector, 0);

for (size_t i = 0; i < edges.size(); ++i) {        igraph_vector_int_push_back(&edge_vector, edges[i]);    }

igraph_add_edges(&graph, &edge_vector, 0);

igraph_vector_t weight_vector;    igraph_vector_init(&weight_vector, 0);

for (size_t i = 0; i < weights.size(); ++i) {        igraph_vector_push_back(&weight_vector, weights[i]);    }

igraph_strvector_t attribute_names;    igraph_strvector_init(&attribute_names, 0);    igraph_strvector_add(&attribute_names, 'weight');

igraph_i_cattribute_add_edges(&graph, 'weight', &weight_vector, &attribute_names);

for (size_t i = 0; i < node_names.size(); ++i) {        igraph_strvector_clear(&attribute_names);        igraph_strvector_add(&attribute_names, 'name');        igraph_i_cattribute_add_vertices(&graph, 'name', i, i + 1, &attribute_names);    }

FILE *outfile = fopen('gg.graphml', 'w');    igraph_write_graph_graphml(&graph, outfile, false);    fclose(outfile);    igraph_destroy(&graph);    igraph_vector_int_destroy(&edge_vector);    igraph_vector_destroy(&weight_vector);    igraph_strvector_destroy(&attribute_names);

return 0