r tidygraph find first parent in hierarchy that meets criteria

Question

Find the first approver within the reporting line which is a minimum of 2 grades higher. Eg grade 0 is two grades higher than grade 2.

Employee Graph

I'm trying to create a new node attribute Approver which should populate for Employees H,E,F,G which should all identify the approver as Employee A.

I've been trying to figure this out all day but don't really get how how to do a one hop traversal let alone several. My understanding is that a breath first search BFS will start from the leaf nodes and then work it's way up the tree. I'm getting really stuck on how to access different parts of the tree.

Any help much appreciated.

library(tidygraph)
library(visNetwork)

# sample graph
g <- tidygraph::create_tree(8,2) %>% 
  activate(nodes) %>% 
  mutate(Employee = LETTERS[1:8],
         Grade = c(0,1,1,1,2,2,2,2),
         label = paste("Emp",Employee,"Grade",Grade)
         )

visIgraph(g,layout="layout_as_tree", flip.y=F,idToLabel = F)

g %>% activate(nodes) %>% 
  mutate(Approver = map_bfs_back(node_is_root(),.f = function(node,path,...){
    #If starting node grade - node grade >= 2 then Approver Employee ID
  }))

score 1 · Accepted Answer · answered Jul 05 '18 at 10:05

Took awhile to figure this out. Not sure if anyone else is interested in this sort of query? Hopefully helpful to someone.

g %>% activate(nodes) %>% 
  mutate(P = map_bfs_chr(node_is_root(),.f = function(node,path, ...){
    .N()$Employee[tail(path$node[ .N()$Grade[node] - .N()$Grade[path$node] >= 2],1)[1]]
  }))

r tidygraph find first parent in hierarchy that meets criteria

1 Answers1