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Return edges.
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@antejavor
antejavor committed Jan 9, 2024
1 parent 2577b02 commit fe8d4cd
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Showing 2 changed files with 43 additions and 16 deletions.
51 changes: 36 additions & 15 deletions cpp/shortest_path_module/algorithm/k_weighted_shortest_paths.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,28 +6,29 @@
#include <unordered_map>
#include "mg_procedure.h"

double KWeightedShortestPaths::GetEdgeWeight(mgp::Node &node1, mgp::Node &node2, const std::string_view &weight_name) {
KWeightedShortestPaths::EdgeWeight KWeightedShortestPaths::GetEdgeWeight(mgp::Node &node1, mgp::Node &node2,
const std::string_view &weight_name) {
for (const auto &relationship : node1.OutRelationships()) {
if (relationship.To() == node2 && relationship.GetProperty(std::string(weight_name)).IsNumeric()) {
return relationship.GetProperty(std::string(weight_name)).ValueNumeric();
return {relationship, relationship.GetProperty(std::string(weight_name)).ValueNumeric()};
}
}
for (const auto &relationship : node1.InRelationships()) {
if (relationship.From() == node2 && relationship.GetProperty(std::string(weight_name)).IsNumeric()) {
return relationship.GetProperty(std::string(weight_name)).ValueNumeric();
return {relationship, relationship.GetProperty(std::string(weight_name)).ValueNumeric()};
}
}
return 0.0;
}

KWeightedShortestPaths::DijkstraResult KWeightedShortestPaths::Dijkstra(
mgp::Graph &graph, mgp::Node &source, mgp::Node &sink, const std::string_view &weight_name,
const std::set<uint64_t> &ignore_nodes, const std::set<std::pair<uint64_t, uint64_t>> &ignore_edges) {
std::unordered_map<uint64_t, double> distances;
std::unordered_map<uint64_t, mgp::Id> previous;
std::unordered_map<uint64_t, mgp::Id> previous_nodes;
std::priority_queue<std::pair<mgp::Node, double>, std::vector<std::pair<mgp::Node, double>>,
KWeightedShortestPaths::CompareWeightDistance>
queue;
std::unordered_map<uint64_t, mgp::Id> previous_edges;
for (const auto &node : graph.Nodes()) {
if (node == source) {
distances[node.Id().AsUint()] = 0;
Expand Down Expand Up @@ -58,22 +59,31 @@ KWeightedShortestPaths::DijkstraResult KWeightedShortestPaths::Dijkstra(

if (alternative_distance < distances[neighbor.Id().AsUint()]) {
distances[neighbor.Id().AsUint()] = alternative_distance;
previous[neighbor.Id().AsUint()] = node.Id();
previous_nodes[neighbor.Id().AsUint()] = node.Id();
previous_edges[neighbor.Id().AsUint()] = relationship.Id();
queue.push({neighbor, distances[neighbor.Id().AsUint()]});
}
}
}

if (previous.find(sink.Id().AsUint()) == previous.end()) {
if (previous_nodes.find(sink.Id().AsUint()) == previous_nodes.end()) {
// Dijkstra's algorithm didn't find a path from the source to the sink
return {{std::numeric_limits<double>::infinity(), {}}};
return {{std::numeric_limits<double>::infinity(), {}, {}}};
}
KWeightedShortestPaths::TempPath shortest_path = {0, {}};
for (mgp::Node node = sink; node != source; node = graph.GetNodeById(previous[node.Id().AsUint()])) {
KWeightedShortestPaths::TempPath shortest_path = {0, {}, {}};
for (mgp::Node node = sink; node != source; node = graph.GetNodeById(previous_nodes[node.Id().AsUint()])) {
shortest_path.vertices.push_back(node);
auto relationships = node.InRelationships();
for (const auto &relationship : relationships) {
if (relationship.Id() == previous_edges[node.Id().AsUint()]) {
shortest_path.edges.push_back(relationship);
break;
}
}
}
shortest_path.vertices.push_back(source);
std::reverse(shortest_path.vertices.begin(), shortest_path.vertices.end());
std::reverse(shortest_path.edges.begin(), shortest_path.edges.end());
shortest_path.weight = distances[sink.Id().AsUint()];

return {shortest_path, distances};
Expand Down Expand Up @@ -101,10 +111,15 @@ std::vector<KWeightedShortestPaths::TempPath> KWeightedShortestPaths::YenKSP(mgp
root_path.vertices.insert(root_path.vertices.end(), prev_shortest_path.vertices.begin(),
prev_shortest_path.vertices.begin() + i + 1);

// Add previous edge weights
for (size_t j = 0; j < root_path.vertices.size() - 1; ++j) {
root_path.weight +=
KWeightedShortestPaths::GetEdgeWeight(root_path.vertices[j], root_path.vertices[j + 1], weight_name);
KWeightedShortestPaths::EdgeWeight edge_weight =
GetEdgeWeight(root_path.vertices[j], root_path.vertices[j + 1], weight_name);
root_path.weight += edge_weight.weight;

root_path.edges.push_back(edge_weight.rel);
}

std::set<uint64_t> ignore_nodes;
std::set<std::pair<uint64_t, uint64_t>> ignore_edges;

Expand All @@ -127,6 +142,7 @@ std::vector<KWeightedShortestPaths::TempPath> KWeightedShortestPaths::YenKSP(mgp
total_path.weight += spur_result.path.weight;
total_path.vertices.insert(total_path.vertices.end(), spur_result.path.vertices.begin() + 1,
spur_result.path.vertices.end());
total_path.edges.insert(total_path.edges.end(), spur_result.path.edges.begin(), spur_result.path.edges.end());

candidates.push(total_path);
}
Expand Down Expand Up @@ -190,11 +206,16 @@ void KWeightedShortestPaths::KWeightedShortestPaths(mgp_list *args, mgp_graph *m
for (auto path : k_shortest_paths) {
mgp::Map path_map{};
path_map.Insert("weight", mgp::Value(path.weight));
mgp::List path_list;
mgp::List path_nodes;
mgp::List path_edges;
for (auto node : path.vertices) {
path_list.AppendExtend(mgp::Value(node));
path_nodes.AppendExtend(mgp::Value(node));
}
for (auto edge : path.edges) {
path_edges.AppendExtend(mgp::Value(edge));
}
path_map.Insert("path", mgp::Value(path_list));
path_map.Insert("path_nodes", mgp::Value(path_nodes));
path_map.Insert("path_edges", mgp::Value(path_edges));

auto record = record_factory.NewRecord();
record.Insert(KWeightedShortestPaths::kResultPaths, path_map);
Expand Down
8 changes: 7 additions & 1 deletion cpp/shortest_path_module/algorithm/k_weighted_shortest_paths.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,12 @@ constexpr const char *kDefaultWeightName = "weight";
struct TempPath {
double weight;
std::vector<mgp::Node> vertices;
std::vector<mgp::Relationship> edges;
};

struct EdgeWeight {
mgp::Relationship rel;
double weight;
};

struct ComparePaths {
Expand Down Expand Up @@ -52,7 +58,7 @@ struct DijkstraResult {
std::unordered_map<uint64_t, double> distances;
};

double GetEdgeWeight(mgp::Node &node1, mgp::Node &node2, const std::string_view &weight_name);
EdgeWeight GetEdgeWeight(mgp::Node &node1, mgp::Node &node2, const std::string_view &weight_name);

DijkstraResult Dijkstra(mgp::Graph &graph, mgp::Node &source, mgp::Node &sink, const std::string_view &weight_name,
const std::set<uint64_t> &ignore_nodes = {},
Expand Down

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