Add b-Suitor algorithm and b-Matching classes #1109

friedagerharz · 2023-08-07T18:21:58Z

Implementation of the sequential b-Suitor algorithm by Khan et al. and required b-matching classes.

BMatching.hpp represents basic properties of a b-matching data structure. It has a similar functionality as the Matching.hpp class. (They could be merged or inherit as 1-matching from b-matching if the performance remains stable.)
BMatcher.hpp is the abstract base class for b-matching algorithms.
BSuitorMatcher.hpp adds the sequential b-Suitor with a b-function. It can be used to compute a b-matching for a given undirected weighted graph and any b. E.g.:

auto G = METISGraphReader{}.read("input/tiny_02.graph");
const int b = 2;
BSuitorMatcher bsm(G, b);
bsm.run();
const auto M = bsm.getBMatching();

computes the 2-matching for the tiny_02 graph

in (vertex_neighbor,edge_weight) METIS-like format with a weight of 19.

fabratu · 2023-10-10T18:10:16Z

networkit/cpp/matching/BMatching.cpp

+    for (node v : G.nodeRange()) {
+        for (index i = 0; i < b.at(i); i++) {
+            node w = data[v][i];
+            if ((v != w) && (w != none) && !G.hasEdge(v, w)) {


Aren't self loops allowed in b-matchings (with b>1)? Also, this can be tested in one loop with the one above.

Yes, undirected simple graphs are considered.

Merged the loops in 14494fe.

fabratu · 2023-10-10T18:12:53Z

networkit/cpp/matching/BMatching.cpp

+    for (node v : G.nodeRange()) {
+        for (index i = 0; i < b.at(i); i++) {
+            node w = data[v][i];
+            if (w != none && std::find(data[w].begin(), data[w].end(), v) == data[w].end()) {


What's the reason for a none matching? If its happening because of #Neighbors(u) < b, maybe you can escape the inner loop early.

Yes. I restructured the BMatching class in 14494fe. Now, there are no more none nodes in the matching and a range based loop is used.

fabratu · 2023-10-10T19:02:21Z

networkit/cpp/matching/BMatching.cpp

+namespace NetworKit {
+
+BMatching::BMatching(const std::vector<count> &b, count z)
+    : data(z, std::vector<node>(b.size(), none)), b(b) {}


The initialization of data looks wrong (b.size() likely equals number of nodes, not number of matchings per node).

Ohhhh yes, thank you. I chaned this to b.at(i) in some other branch but I completely forgot to cherry pick this commit. Added it now.

networkit/cpp/matching/test/MatcherGTest.cpp

fabratu · 2023-10-10T19:05:02Z

include/networkit/matching/BSuitorMatcher.hpp

+        if (self < v.id)
+            weight += v.weight;
+        if (size == max_size && !list.empty()) {
+            min = *std::min_element(list.begin(), list.end(), [](const Node &a, const Node &b) {


Be consistent concerning lambda function parameter names. This makes the code more readable. Also b is already used for the node variable matching indicators. Better not reuse it in another related context.

Change some names in cb0aa0e including this one.

fabratu · 2023-10-11T14:18:45Z

networkit/cpp/matching/BMatching.cpp

+        data[u][i] = v;
+    }
+    {
+        auto i = findFirstFreeIndex(v);


There is a lot of std::find done in the code. Even though b is likely to be small, have you checked whether std::set (or a struct based on it) is a faster solution?

Restructured BMatching in 14494fe. Used std::set instead.

networkit/cpp/matching/BSuitorMatcher.cpp

fabratu · 2023-10-11T14:23:20Z

include/networkit/matching/BMatching.hpp

+    std::vector<count> getB() const;
+
+protected:
+    std::vector<std::vector<node>> data;


I suggest using a more precise name for class member variables.

done in 14494fe.

fabratu · 2023-10-11T14:24:02Z

include/networkit/matching/BSuitorMatcher.hpp

+    void buildBMatching();
+
+private:
+    std::vector<std::unique_ptr<Suitors>> S;


I suggest not using single char names for class member variables.

I'll change it.

done in cb0aa0e.

include/networkit/matching/BSuitorMatcher.hpp

angriman

Thank you, I left some comments.

angriman · 2024-01-06T11:16:37Z

include/networkit/matching/BMatching.hpp

+    const std::vector<std::set<node>> &getMatches() const;
+    std::vector<count> getB() const;


These are public functions, please add proper documentation.

angriman · 2024-01-06T11:27:59Z

include/networkit/matching/BMatching.hpp

+    std::vector<count> getB() const;
+
+protected:
+    std::vector<std::set<node>> matches;


Do you need to keep the matches sorted? If not, I think we could use a std::unordered_set.

angriman · 2024-01-06T11:33:08Z

include/networkit/matching/BSuitorMatcher.hpp

+
+namespace NetworKit {
+
+struct Node {


This defines a NetworKit::Node struct. I think that this name is too generic for a struct used only by this class. I suggest using something more specific, e.g., WeightedNode, or moving these structs into the BSuitorMatcher.

angriman · 2024-01-06T11:34:52Z

include/networkit/matching/BSuitorMatcher.hpp

+        if (partners.size() < max_size) {
+            return {none, 0};
+        } else {
+            auto ret = min;


More readable:

Suggested change

auto ret = min;

Node min_copy = min;

angriman · 2024-01-06T11:35:45Z

include/networkit/matching/BSuitorMatcher.hpp

+                                          if (v.id == u) {
+                                              return true;
+                                          }
+                                          return false;


Suggested change

if (v.id == u) {

return true;

}

return false;

return v.id == u;

angriman · 2024-01-06T16:20:45Z

networkit/cpp/matching/BSuitorMatcher.cpp

+
+    for (auto n : G->weightNeighborRange(u)) {
+        const Node v = Node(n.first, n.second);
+        if (!hasProposedTo(v.id)) {


You can save an indentation level with:

Suggested change

if (!hasProposedTo(v.id)) {

if (hasProposedTo(v.id)) continue;

angriman · 2024-01-06T16:21:16Z

networkit/cpp/matching/BSuitorMatcher.cpp

+        const Node v = Node(n.first, n.second);
+        if (!hasProposedTo(v.id)) {
+            if (v.weight > best.weight || (v.weight == best.weight && v.id < best.id)) {
+                const auto n_suitor_weight = Suitors.at(v.id)->min.weight;


Suggested change

const auto n_suitor_weight = Suitors.at(v.id)->min.weight;

const edgeweight n_suitor_weight = Suitors.at(v.id)->min.weight;

angriman · 2024-01-06T16:23:04Z

networkit/cpp/matching/BSuitorMatcher.cpp

+    G->forNodes([&](node u) {
+        G->forNodes([&](node v) {


You can stop iterating once sym is false. I suggest replacing these two loops with two for (node u : G->nodeRange()) loops and break once sym is false.

angriman · 2024-01-06T16:23:57Z

networkit/cpp/matching/BSuitorMatcher.cpp

+    // TODO make parallel
+    G->forNodes([&](node x) {
+        assert(Suitors.at(x)->partners.size() <= b.at(x));
+        for (auto y : Suitors.at(x)->partners) {


Suggested change

for (auto y : Suitors.at(x)->partners) {

for (node y : Suitors.at(x)->partners) {

angriman · 2024-01-06T16:25:31Z

include/networkit/matching/BSuitorMatcher.hpp

+     */
+    void run() override;
+
+    void buildBMatching();


Missing documentation.

friedagerharz force-pushed the frieda/b-suitor branch 3 times, most recently from 1d26d92 to bccb01f Compare August 10, 2023 14:48

fabratu added the new feature label Aug 11, 2023

friedagerharz force-pushed the frieda/b-suitor branch 4 times, most recently from f8d17a9 to c7fde94 Compare August 23, 2023 22:10

friedagerharz force-pushed the frieda/b-suitor branch 2 times, most recently from d342c99 to b993e0e Compare September 15, 2023 00:23

friedagerharz force-pushed the frieda/b-suitor branch 4 times, most recently from 7e34f0b to 18f97b0 Compare September 25, 2023 08:17

friedagerharz mentioned this pull request Sep 25, 2023

Add MTXGraphReader #1132

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friedagerharz marked this pull request as ready for review September 25, 2023 10:52

friedagerharz requested a review from fabratu September 25, 2023 17:24

friedagerharz force-pushed the frieda/b-suitor branch 4 times, most recently from aae6c0c to c66a1fe Compare September 29, 2023 11:36

Frieda Gerharz added 9 commits October 3, 2023 13:06

add bMatching & bSuitor classes

d910175

add and split up unit tests

b45bd3d

allow different b values for individual nodes

d8af931

fixup! allow different b values for individual nodes

cb59ff7

fix typo; drop superfluous this/copy

1b72c7a

parallelize bMatching weight getter

974aa17

change suitor/proposed structure

3d45e1e

fixup! change suitor/proposed structure

aa8b351

fix weight getter

5078de7

Frieda Gerharz added 2 commits October 3, 2023 13:06

use smart pointers

4bb95ce

restructure

91c4bfd

friedagerharz force-pushed the frieda/b-suitor branch from 058d191 to 91c4bfd Compare October 3, 2023 11:11

fabratu requested changes Oct 11, 2023

View reviewed changes

Frieda Gerharz added 3 commits October 12, 2023 16:14

fix: bMatching size; bMatching symmetry check

25953bd

remove weight calculation; change and rename some types;

cb0aa0e

restructure Matching class

14494fe

friedagerharz force-pushed the frieda/b-suitor branch from bf9d6ee to ffb09b9 Compare November 14, 2023 14:15

fix

8ce89d4

friedagerharz force-pushed the frieda/b-suitor branch from ffb09b9 to 8ce89d4 Compare November 15, 2023 13:08

angriman requested changes Jan 6, 2024

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Add b-Suitor algorithm and b-Matching classes #1109

Add b-Suitor algorithm and b-Matching classes #1109

friedagerharz commented Aug 7, 2023 •

edited

fabratu Oct 10, 2023

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		const std::vector<std::set<node>> &getMatches() const;
		std::vector<count> getB() const;

	if (!hasProposedTo(v.id)) {
	if (hasProposedTo(v.id)) continue;

	const auto n_suitor_weight = Suitors.at(v.id)->min.weight;
	const edgeweight n_suitor_weight = Suitors.at(v.id)->min.weight;

	for (auto y : Suitors.at(x)->partners) {
	for (node y : Suitors.at(x)->partners) {

Add b-Suitor algorithm and b-Matching classes #1109

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Add b-Suitor algorithm and b-Matching classes #1109

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friedagerharz commented Aug 7, 2023 • edited

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friedagerharz commented Aug 7, 2023 •

edited