How arrange diagram in R

Question

I want to get diagram similar to picture below, but code I use creates different diagram. With rbind I added some hierarchy to a diagram. In data frame col0 there is a string with names of animals. In col1 string is split into individual animals & col2 is adding latin name for a animal. col1 data are always changing and in col2 data constant (there always be feline or canis names in that column).

library(igraph)
# I create my dataframe with animals
df <- data.frame(col0 = c("Cat Dog Wolf", "Cat Dog Wolf", "Cat Dog Wolf"),
col1 = c( "Cat", "Dog", "Wolf"),
col2 = c( "Feline", "Canis", "Canis2"))
# Add extra lines for hierarchy 
# These lines work with current graph for a new one these should be replace or deleted
df <-rbind(df, data.frame(col0 = "Cat Dog Wolf", col1 = "Feline", col2 ="Animal"))
df <-rbind(df, data.frame(col0 = "Cat Dog Wolf", col1 = "Canis", col2 = "Animal"))
df <-rbind(df, data.frame(col0 = "Cat Dog Wolf", col1 = "Canis2", col2 = "Canis"))

##########
df <-df[c('col2', 'col1')]
names(df) <-c('from', 'to')
abc <-union(df$to, df$from)
###########

g <-graph.data.frame(df, directed = TRUE, vertices = abc)
plot(g, vertex.size = 20, vertex.label.dist = 0.5, vertex.color = c("blue", 
"red", "green", "white", "orange"  ),
edge.arrow.size = 0.5, layout = layout.reingold.tilford(g))

This is the graph that the above code outputs, but it's not quite what I want:

I want a similar diagram to what's shown below:

Answer 1

I think that I understand what you want, but I will restate the problem so that you can confirm whether or not I understood. I think that what you want to do is this:

Find all of the leaves in the tree, i.e. the nodes with no descendants. Each leaf will have one parent. Rename the parent with the name of the leaf, then delete the leaf from the graph. The following code implements that.

## Assume that we have created the graph g using your code
g2 = g           # Keep original graph intact
SourceNodes = sapply(strsplit(attr(E(g2), "vnames"), "\\|"), "[", 1)
DestNodes = sapply(strsplit(attr(E(g2), "vnames"), "\\|"), "[", 2)

## Leaf nodes are nodes that are destinations, but not sources
## Also need the node numbers for later deletion
(LeafNodes = DestNodes[which(!(DestNodes%in% SourceNodes ))])
[1] "Cat"  "Dog"  "Wolf"
(LeafNumbers = match(LeafNodes, attr(V(g), "name")))
[1] 1 2 3

## Find the parents of the leaves
(UpOne = SourceNodes[match(LeafNodes, DestNodes)])
[1] "Feline" "Canis"  "Canis2"

## Rename the UpOne nodes (parents of leaves)
vertex_attr(g2)$name[match(UpOne, vertex_attr(g2)$name)] = LeafNodes

## Now delete the leaf nodes and plot
g2 = delete_vertices(g2, LeafNumbers)
plot(g2, vertex.size = 20, vertex.label.dist = 0.5, 
    vertex.color = c("red", "green", "white", "orange"  ),
    edge.arrow.size = 0.5, layout = layout.reingold.tilford(g2))

Result