Feature request: facet_components

[wdkrnls]

The current faceting tools force keeping all nodes presented (if invisibly) on all facets. I'm looking for the functionality to analyze my graph by breaking it up into subgraphs. My strategy so far has been to try and isolate these subgraphs by cutting edges to produce completely disconnected components. I have managed a hack using facet_nodes which only shows the nodes and edges of each component, but each facet has massive whitespace gaps where the other components would be. Reading through issue #136 it seems that my request is slightly different, because I not only want to change what nodes (and edges) appear across facets, but also seek to reposition the location of nodes shown across each facet to focus on each component in isolation. Does that make sense? I suspect you might want a new facetting function facet_components to do this. I would also prefer to have some way to show groups of similar components shown together in a facet_grid style arrangement as well.

[mkoohafkan]

I think this will be related to igraph::component_wise. Or perhaps it involves adding an offset to the coordinates generated by create_layout(), so that the result is achievable via facet_wrap(scales = "free").

Technically this is possible using facet_wrap(), you just need to assign the component ID as an attribute of both the nodes and the edges:

g1 = create_ring(10) %N>%
  mutate(label = "A") %E>%
  mutate(label = "A")
g2 = create_ring(5) %N>%
  mutate(label = "B") %E>%
  mutate(label = "B")

g = bind_graphs(g1, g2)
ggraph(g) +
  geom_edge_link() +
  geom_node_point() +
  facet_wrap(~label, scales = "free")

[thomasp85]

You can do this directly with facet_nodes() using tidygraph algorithms

g <- bind_graphs(create_ring(10), create_ring(5))
ggraph(g) +
  geom_edge_link() +
  geom_node_point() +
  facet_nodes(~tidygraph::group_components(), scales = "free")
#> Using "stress" as default layout