Create a network of unconnected, very small, full connected components

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My final aim would be an undirected edgelist of this kind:

Per a network of 3 components, full connected, one with 1 node, one with 2 nodes, one with 3 nodes:

There would be 6 nodes, but since the first component is made only of 1 node, node1 has no edges.

tibble(from = c(2,4,4,5),
       to = (3,5,6,6)
)

But the number of components may higher then 3, let's say 30. The average number of edges within component would be ruled after rpois(30,1)+1.

In tidygraph, the function to create a complete graph would be create_complete, and in theory I could just keep generating complete graph and binding their edgelist. But in that case I would have a problem of naming the edges, and I could miss the unconnected nodes.

tidygraph igraph r
1 Answers

Update

If you want to show the cluster labels, you can use membership + components to add this attribute like below

set.seed(1)
do.call(
  graph.disjoint.union,
  lapply(
    rpois(30, 1) + 1,
    make_full_graph
  )
) %>%
  set_vertex_attr(name = "names", value = seq(vcount(.))) %>%
  set_vertex_attr(name = "cluster_label", value = membership(components(.))) %>% 
  as_tbl_graph(directed = FALSE)

which gives

# A tbl_graph: 62 nodes and 49 edges
#
# An undirected simple graph with 30 components
#
# Node Data: 62 x 2 (active)
  names cluster_label
  <int>         <dbl>
1     1             1
2     2             2
3     3             2
4     4             3
5     5             3
6     6             4
# ... with 56 more rows
#
# Edge Data: 49 x 2
   from    to
  <int> <int>
1     2     3
2     4     5
3     6     7
# ... with 46 more rows

You can use disjoint.union + make_full_graph like below (assuming you have 3 fully connected components with 1,2, and 3 nodes respectively)

library(tidygraph)
library(igraph)
do.call(
  graph.disjoint.union,
  lapply(
    1:3,
    make_full_graph
  )
) %>%
  set_vertex_attr(name = "names", value = seq(vcount(.))) %>% 
  as_tbl_graph(directed = FALSE)

which gives you

# A tbl_graph: 6 nodes and 4 edges
#
# An undirected simple graph with 3 components
#
# Node Data: 6 x 1 (active)
  names
  <int>
1     1
2     2
3     3
4     4
5     5
6     6
#
# Edge Data: 4 x 2
   from    to
  <int> <int>
1     2     3
2     4     5
3     4     6
# ... with 1 more row

Regarding the use of rpois(30,1)+1, perhaps this could help if you replace 1:3 with rpois(30,1)+1, e.g.,

set.seed(1)
do.call(
  graph.disjoint.union,
  lapply(
    rpois(30,1)+1,
    make_full_graph
  )
) %>%
  set_vertex_attr(name = "names", value = seq(vcount(.))) %>% 
  as_tbl_graph(directed = FALSE)

and a graph is generated with the following info

# A tbl_graph: 62 nodes and 49 edges
#
# An undirected simple graph with 30 components
#
# Node Data: 62 x 1 (active)
  names
  <int>
1     1
2     2
3     3
4     4
5     5
6     6
# ... with 56 more rows
#
# Edge Data: 49 x 2
   from    to
  <int> <int>
1     2     3
2     4     5
3     6     7
# ... with 46 more rows
user_121587570
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