I am trying to add some edge attributes to a GraphViz graph using the DiagrammeR package in R. In particular, I want to add the attributes arrowhead and weight, but only the former is added to the graph but not the latter. The example below is not real one, but a super-reduced version of it for the sake of reproducibility and clarity.
library(tidyverse)
library(DiagrammeR)
# create nodes
nd <- tibble(
label = c("A", "B", "C", "D"),
rank = c("1", "0", "2", "2")
)
node <- create_node_df(
n = nrow(nd),
label = nd$label,
id = c(1:nrow(nd)),
# rank = nd$rank
)
# create edges
ed <- tribble(
~from, ~to, ~arrowhead, ~weight,
1, 2, 'normal', "5",
1, 3, 'normal', "1",
3, 4, 'normal', "1",
3, 2, 'normal', "1"
)
edge <- create_edge_df(
from = ed$from,
to = ed$to,
arrowhead = ed$arrowhead,
weight = ed$weight
)
# create graph
graph <-
create_graph(
nodes_df = node,
edges_df = edge) %>%
add_global_graph_attrs(
attr = "overlap",
value = "false",
attr_type = "graph") %>%
add_global_graph_attrs(
attr = "layout",
value = "dot",
attr_type = "graph")
Yet, when I generate the dot code, the weight attribute is not part of the edges but arrowhead is.
graph %>%
generate_dot() %>%
cat()
#> digraph {
#>
#> graph [layout = 'dot',
#> outputorder = 'edgesfirst',
#> bgcolor = 'white',
#> overlap = 'false']
#>
#> node [fontname = 'Helvetica',
#> fontsize = '10',
#> shape = 'circle',
#> fixedsize = 'true',
#> width = '0.5',
#> style = 'filled',
#> fillcolor = 'aliceblue',
#> color = 'gray70',
#> fontcolor = 'gray50']
#>
#> edge [fontname = 'Helvetica',
#> fontsize = '8',
#> len = '1.5',
#> color = 'gray80',
#> arrowsize = '0.5']
#>
#> '1' [label = 'A']
#> '2' [label = 'B']
#> '3' [label = 'C']
#> '4' [label = 'D']
#> '1'->'2' [arrowhead = 'normal']
#> '1'->'3' [arrowhead = 'normal']
#> '3'->'4' [arrowhead = 'normal']
#> '3'->'2' [arrowhead = 'normal']
#> }
I also tried adding the attribute using set_edge_attrs() and it is still not working.
graph <- graph %>%
set_edge_attrs(edge_attr = "weight",
values = "5",
from = 1,
to = 2
)
# digraph {
#
# graph ...
# {trimmed output}
#
# '1'->'2' [arrowhead = 'normal']
# '1'->'3' [arrowhead = 'normal']
# '3'->'4' [arrowhead = 'normal']
# '3'->'2' [arrowhead = 'normal']
# }
In the end, I had to modify the dot code by hand (see below), but It is not ideal given that I have to produce several diagrams from info in data frames.
graph2 <- "digraph {
graph [layout = 'dot',
outputorder = 'edgesfirst',
bgcolor = 'white',
overlap = 'false']
node [fontname = 'Helvetica',
fontsize = '10',
shape = 'circle',
fixedsize = 'true',
width = '0.5',
style = 'filled',
fillcolor = 'aliceblue',
color = 'gray70',
fontcolor = 'gray50']
edge [fontname = 'Helvetica',
fontsize = '8',
len = '1.5',
color = 'gray80',
arrowsize = '0.5']
'1' [label = 'A']
'2' [label = 'B']
'3' [label = 'C']
'4' [label = 'D']
'1'->'2' [arrowhead = 'normal', weight = 5]
'1'->'3' [arrowhead = 'normal', weight = 0]
'3'->'4' [arrowhead = 'normal', weight = 0]
'3'->'2' [arrowhead = 'normal', weight = 0]
}
"
grViz(graph2)
I highly appreciate any help.
Thanks. Best,
I'm not sure if it is a bug or if "weight" is being ignored deliberately, but anyway the culprit is a helper function in DiagrammeR that generates a vector of allowed attributes and generate_dot() only allows attributes from that vector.
# DiagrammeR/R/utils.R
gv_edge_attributes <- function() {
c("style", "penwidth", "color", "arrowsize",
"arrowhead", "arrowtail",
"fontname", "fontsize", "fontcolor",
"len", "tooltip", "URL",
"label", "labelfontname", "labelfontsize",
"labelfontcolor", "labeltooltip", "labelURL",
"edgetooltip", "edgeURL",
"headtooltip", "headURL",
"headclip", "headlabel", "headport",
"tailtooltip", "tailURL",
"tailclip", "taillabel", "tailport",
"dir", "decorate")
}
If you add "weight" to that list – or modify the generate_dot to allow all attributes without checks –, your example works just fine.