Basic Circle packing with several hierarchy level



This page is dedicated to multi level circle packing. It explains how to build one using R and the ggraph package.

Circle Packing section Data to Viz

Input & concept


Circular packing represents a hierarchy: The biggest circle (origin of the hierarchy) contains several big circles (nodes of level 1), which contain smaller circle (level 2) and so on.. The last level is called leaf.

The input data is a list of edges between nodes. It should look more or less like the table beside. Moreover, we usually accompany this table with another one that gives features for each node.

Edge list

Edge list

Most basic circular packing with ggraph


The ggraph package makes it a breeze to build a circular packing from an edge list. Here is an example based on the flare dataset proovded with the package.

The first step is to transform the dataframe to a graph object thanks to the graph_from_data_frame() function of the igraph package. Then, ggraph offers the geom_node_circle() function that will build the chart.

# Libraries
library(ggraph)
library(igraph)
library(tidyverse)
 
# We need a data frame giving a hierarchical structure. Let's consider the flare dataset:
edges <- flare$edges
 
# Usually we associate another dataset that give information about each node of the dataset:
vertices <- flare$vertices
 
# Then we have to make a 'graph' object using the igraph library:
mygraph <- graph_from_data_frame( edges, vertices=vertices )
 
# Make the plot
ggraph(mygraph, layout = 'circlepack') + 
  geom_node_circle() +
  theme_void()

Switching to another chart type


Note that the ggraph library allows to easily go from one type of representation to another. Indeed several types of representation are suitable for hierarchical data: dendrogram (can be circular), treemap, sunburst diagram or network!

ggraph(mygraph, layout='dendrogram', circular=TRUE) + 
  geom_edge_diagonal() +
  theme_void() +
  theme(legend.position="none")
ggraph(mygraph, layout='dendrogram', circular=FALSE) + 
  geom_edge_diagonal() +
  theme_void() +
  theme(legend.position="none")
ggraph(mygraph, 'treemap', weight = size) + 
  geom_node_tile(aes(fill = depth), size = 0.25) +
  theme_void() +
  theme(legend.position="none")
ggraph(mygraph, 'partition', circular = TRUE) + 
  geom_node_arc_bar(aes(fill = depth), size = 0.25) +
  theme_void() +
  theme(legend.position="none")
ggraph(mygraph) + 
  geom_edge_link() + 
  geom_node_point() +
  theme_void() +
  theme(legend.position="none")

Related chart types


Grouped and Stacked barplot
Treemap
Doughnut
Pie chart
Dendrogram
Circular packing



Contact

This document is a work by Yan Holtz. Any feedback is highly encouraged. You can fill an issue on Github, drop me a message on Twitter, or send an email pasting yan.holtz.data with gmail.com.

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