How to add Axis labels using networkD3 in R

Last Updated : 28 Jun, 2022

networkD3 is an R package used for creating a D3 (Data-Driven Documents) Network Graph. netwrorkD3 is constructed using the htmlwidget package. As the name said network, this graph can be constructed in the shape of a node and edge data frame. then it will perform a physics simulation to decide the most advantageous diagram in three dimensions. It is used to create a D3 Javascript network, tree, dendrogram, Sankey graph, etc.

In the R package, there are already many visualization libraries present. For example ggplot, Plotly, igraph, etc. But not all libraries are used to create network-type graphs and it is also not in 3D plots. That is the main objective behind why it is made.

Syntax: sankeyNetwork( Links, Nodes, Source, Target, Value, NodeID, NodeGroup = NodeID, LinkGroup = NULL, units = “”, colourScale = NULL, fontSize = 7, fontFamily = NULL, nodeWidth = 15, nodePadding = 10, margin = NULL, height = NULL, width = NULL, iterations = 32, sinksRight = TRUE )

Parameters:

Links: dataframe represent link between source and target (node).

Nodes: dataframe contain node properties

Source: character string of source node

Target: character string of target node

Value: character string of distance value between nodes

NodeID: node name

NodeGroup: character string of the nodeIDs in nodes

LinkGroup: character string for link between groups

Units: character string to specify physical unit(value)

colourscale: specify color scale

nodeWidth: width of node

nodePadding: padding between node

sinksRight: Boolean. If it is True, last node moves to right border of graph

Creating a simple sankeyNetwork graph with Title, Subtitle, and Labels

Step: 1 Import the necessary library in Rstudio.

R

library(dplyr)
library(networkD3)
library(htmlwidgets)
library(manipulateWidget)
library(htmltools)

Step: 2 Create network data in a source-target data frame format.

Here, we are linking A->D, B->E, and C->F nodes and assigning 3 values on each link. final table will look like myDataframe table image.
The node table is containing every node entry uniquely.
IDsource and IDtarget is a string character form of the source and the target node.
match function will match take two-column and create a matching table from 1. But we are subtracting by ‘-1’ so that it can start with 0th character like for A node it is 0, B node it is 1 and so on.

R

# Create values
Source_Node <- c("A","B","C","A","B",
                 "C","A","B","C")
Target_category <- c("D","E","F","D",
                     "E","F","D","E","F")
Frequency <- c(1,2,3,4,5,6,7,8,9)
myDataframe <- data.frame(Source_Node,
                          Target_category,Frequency)
 
# Node table
nodes <- data.frame(name=c(as.character(myDataframe$Source_Node), 
                           as.character(myDataframe$Target_category))
                    %>% unique())
 
# IDsource and IDtarget string character format
myDataframe$IDsource=match(myDataframe$Source_Node, 
                           nodes$name)-1 
myDataframe$IDtarget=match(myDataframe$Target_category,
                           nodes$name)-1

Output:

Step: 3 Create a simple Sankey network chart.

As per the above sankeyNetwork syntax, we are assigning some parameters to generate our output.

R

graph1 <- sankeyNetwork(Links = myDataframe,  
                        Nodes = nodes, 
                   Source = "IDsource", 
                        Target = "IDtarget", 
                   Value = "Frequency",
                        NodeID = "name",  
                   sinksRight=FALSE)
 
# view graph
graph1

Output:

SankeyNetwork Graph

Step: 4 Add Title and Subtitle in graph1.

To assign a title, we can use the prependContent function from the htmlwidgets tool.
Create two h1 and h2 tags with text description and style.
prepend these tags in our above graph1 by putting all these tags together in the prependContent function.

R

graph2 <- htmlwidgets::prependContent(graph1, 
                                      htmltools::tags$h1(
                                        "GeeksForGeeks Title",
                                      style="text-align:center; 
color:#007500; "),
                                      htmltools::tags$h2(
                                        "GeeksForGeeks Subtitle",
                                      style="color:#00D100; 
text-align:center;"))
 
# view graph
graph2

Output:

SankeyNetwork graph with title and subtitle

Step: 5 Add left and right labels in networkGraph.

create left-tag as leftTx and right-tag as rightTx.
Now, to combine leftTx, rightTx and graph2, use combineWidget from manipulatewidget library.
combineWidget take, graph, title, left-column, right-column, and row-number as parameters and combine all these instances into one.

Syntax: combineWidgets( list = NULL, nrow = NULL, ncol = NULL, title = NULL, rowsize = 1, colsize = 1, byrow = TRUE, titleCSS = “”, header = NULL, footer = NULL, leftCol = NULL, rightCol = NULL, width = NULL, height = NULL )

R

# create left-right label 
leftTx = tags$div( 
         style="max-width: 30vw; height: 100%; 
                 display: flex; align-items: center; 
                 justify-content: center;", 
         tags$p("This is left side label"))
 
rightTx = tags$p("This is right side label",
                   style="max-width:30vw")
 
# final output with label. combineWidget
# can be use by manipulateWidget.
graph3 <- combineWidgets(graph2,
                      title = tags$h1("With left-right label",
                      style="text-align:center;color:#007500;"),
                      leftCol = leftTx,
                      rightCol = rightTx,
                      nrow = 1)
 
# view graph
graph3