laziness factor

kaminpar-cli/kaminpar_arguments.cc

@@ -162,6 +162,10 @@ CLI::Option_group *create_coarsening_options(CLI::App *app, Context &ctx) {
       new number of edges <= factor * old number of edges
       The default is infinity.)"
     );
+  coarsening->add_option("--s-laziness-factor", ctx.sparsification.laziness_factor)
+  ->default_val(1.)
+  ->description(R"(Only sparsify if the number of edges times the laziness factor are less than the target.
+      Thus greater laziness leads to less sparsification. The default is 1.)");
 
 
   coarsening->add_flag("--s-no-approx", ctx.sparsification.no_approx)

kaminpar-shm/coarsening/sparsifing_cluster_coarsener.cc

@@ -128,7 +128,7 @@ bool SparsifyingClusteringCoarsener::coarsen() {
     );
   }
 
-  if (coarsened->get().m() > target_edge_amount) { // sparsify
+  if (coarsened->get().m() > _s_ctx.laziness_factor * target_edge_amount) { // sparsify
     KASSERT(coarsened->get().m() % 2 == 0, "graph should be undirected", assert::always);
 
     const CSRGraph *csr = dynamic_cast<const CSRGraph *>(coarsened->get().underlying_graph());

kaminpar-shm/kaminpar.h

@@ -234,6 +234,7 @@ struct SparsificationContext {
 
   float density_target_factor;
   float reduction_target_factor;
+  float laziness_factor;
 
   bool no_approx;