Add group_color

NAMESPACE

@@ -221,6 +221,7 @@ export(graph_size)
 export(graph_unconn_count)
 export(group_biconnected_component)
 export(group_by)
+export(group_color)
 export(group_components)
 export(group_data)
 export(group_edge_betweenness)
@@ -519,6 +520,7 @@ importFrom(igraph,graph_from_adjacency_matrix)
 importFrom(igraph,graph_from_data_frame)
 importFrom(igraph,graph_from_edgelist)
 importFrom(igraph,graph_from_incidence_matrix)
+importFrom(igraph,greedy_vertex_coloring)
 importFrom(igraph,gsize)
 importFrom(igraph,harmonic_centrality)
 importFrom(igraph,has_eulerian_cycle)

NEWS.md

@@ -31,6 +31,7 @@
 * Added `centrality_harmonic()` + deprecated `centrality_closeness_harmonic()`.
   The latter is an interface to netrankr while the former is a more efficient 
   and flexible igraph implementation.
+* Added `group_color()` as an interface to `greedy_vertex_coloring()` in igraph
 
 # tidygraph 1.2.3
 

R/group.R

@@ -203,6 +203,17 @@ group_biconnected_component <- function() {
   group <- rep(seq_along(ind), lengths(ind))[order(unlist(ind))][focus_ind(.G(), 'edges')]
   desc_enumeration(group)
 }
+#' @describeIn group_graph Groups nodes by their color using [igraph::greedy_vertex_coloring()]. Be aware that this is not a clustering algorithm as coloring specifically provide a color to each node so that no neighbors have the same color
+#' @importFrom igraph greedy_vertex_coloring
+#' @export
+group_color <- function() {
+  expect_nodes()
+  graph <- .G()
+  group <- greedy_vertex_coloring(graph)
+
+  group <- as.integer(group[focus_ind(.G(), 'nodes')])
+  desc_enumeration(group)
+}
 
 
 # HELPERS -----------------------------------------------------------------

tests/testthat/test-group.R

@@ -20,6 +20,7 @@ test_that("grouping returns integer vector", {
   #expect_type(get_group(gr, group_optimal()), 'integer')
   expect_type(get_group(gr, group_spinglass()), 'integer')
   expect_type(get_group(gr, group_walktrap()), 'integer')
+  expect_type(get_group(gr, group_color()), 'integer')
   gr1 <- activate(gr, edges)
   expect_type(get_group(gr1, group_biconnected_component()), 'integer')
 
@@ -37,6 +38,7 @@ test_that("grouping returns integer of correct length", {
   #expect_length(get_group(gr, group_optimal()), igraph::gorder(gr))
   expect_length(get_group(gr, group_spinglass()), igraph::gorder(gr))
   expect_length(get_group(gr, group_walktrap()), igraph::gorder(gr))
+  expect_length(get_group(gr, group_color()), igraph::gorder(gr))
   gr1 <- activate(gr, edges)
   expect_length(get_group(gr1, group_biconnected_component()), igraph::gsize(gr1))
 
@@ -56,6 +58,7 @@ test_that("grouping requires correct activation", {
   #expect_error(get_group(gr1, group_optimal()))
   expect_error(get_group(gr1, group_spinglass()))
   expect_error(get_group(gr1, group_walktrap()))
+  expect_error(get_group(gr1, group_color()))
 
   skip_on_os('windows')
   expect_error(get_group(gr1, group_leading_eigen()))