Put line break in node labels in networkD3 sankey diagram

Question

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Update: I think the answer to my question is that you can't put line breaks in. A colleague pointed out to me the node labels are SVG blocks, which don't support line breaks.

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How do I put a line break into the node labels for a sankey diagram produced using the networkD3 R package?

Borrowing the example from Place text values to right of sankey diagram I can add values to the lables:

library(networkD3)
library(data.table)
set.seed(1999)
links <- data.table(
  src = rep(0:4, times=c(1,1,2,3,5)),
  target = sample(1:11, 12, TRUE),
  value = sample(100, 12)
)[src < target, ]  # no loops
nodes <- data.table(name=LETTERS[1:12])

#### Need to hover to get counts
##sankeyNetwork(Links=links, Nodes=nodes, Source='src', Target='target',
##  Value='value', NodeID='name', fontSize=16)

## Add text to label
txt <- links[, .(total = sum(value)), by=c('target')]
nodes[txt$target+1L, name := paste0(name, ' (', txt$total, ')')]

## Displays the counts as part of the labels
sankeyNetwork(Links=links, Nodes=nodes, Source='src', Target='target',
  Value='value', NodeID='name', fontSize=16, width=600, height=300)

I hoped that I could naively adjust the paste0 to include a line break character, such as:

 name := paste0(name, "\n ", txt$total)

or

name := paste0(name, "<br/> ", txt$total)

But I haven't been able to get anything to work, and my JavaScript is too rusty to try and fix it once it is produced.

Answer 1

You could replace the SVG text elements with <foreignObject> blocks of text/html. This example would need a lot of additional formatting/positioning to be useful, but it demonstrates that it is possible...

library(networkD3)
library(htmlwidgets)
library(data.table)

set.seed(1999)
links <- data.table(
  src = rep(0:4, times=c(1,1,2,3,5)),
  target = sample(1:11, 12, TRUE),
  value = sample(100, 12)
)[src < target, ]  # no loops
nodes <- data.table(name=LETTERS[1:12])

## Add text to label
txt <- links[, .(total = sum(value)), by=c('target')]
nodes[txt$target+1L, name := paste0(name, '<br>(', txt$total, ')')]

## Displays the counts as part of the labels
sn <- sankeyNetwork(Links=links, Nodes=nodes, Source='src', Target='target',
              Value='value', NodeID='name', fontSize=16, width=600, height=300)

onRender(sn,
         '
  function(el,x) {
    d3.selectAll(".node text").remove()
    d3.selectAll(".node")
      .append("foreignObject")
      .attr("width", 100)
      .attr("height", 50)
      .html(function(d) { return d.name; })
  }
  '
)