Plot Dendrogram with R and ggraph
In this article, we are going to see how to customize dendrogram. It is also known as a tree diagram and it is a visual representation of the hierarchical relationship between items. A dendrogram's main purpose is to figure out the best approach to assign objects to clusters.
Creating Basic Dendrogram
To create a dendrogram we will igraph package which is used for creating and manipulating graphs and analyzing networks graph. So for creating a dendrogram, we will create a dataframe into the hierarchical data structure and then transform it into an edge list. To plot a Dendrogram we will use the following syntax:
ggraph(dataset, layout)
Parameters:
- Dataframe: Hierarchical dataset/vector
- layout: Dimension of layout
- Circular: True/False
Syntax to install and import igraph package in the R working console:
install.package('igraph')
library(igraph)
There are some optional functions to create edge into diagonal we will use geom_edge_diagonal() methods and to add nodes into a graph we will use geom_node_point() methods.
# libraries
library(ggraph)
library(igraph)
library(tidyverse)
# create a data frame
data <- data.frame(
level1="CEO",
level2=c( rep("boss1",4), rep("boss2",4)),
level3=paste0("mister_", letters[1:8])
)
# transform it to a edge list!
edges_level1_2 <- data %>% select(
level1, level2) %>% unique %>% rename(
from=level1, to=level2)
edges_level2_3 <- data %>% select(
level2, level3) %>% unique %>% rename(
from=level2, to=level3)
edge_list=rbind(edges_level1_2, edges_level2_3)
# Now we can plot that
graph_Data <- graph_from_data_frame( edge_list )
ggraph(graph_Data, layout = 'dendrogram', circular = FALSE) +
geom_edge_diagonal() +
geom_node_point() +
theme_void()
Output:
Circular Layout Dendrogram
To create a circular layout we will use circular = True, which will plot it into the circular layout.
# libraries
library(ggraph)
library(igraph)
library(tidyverse)
# create a data frame
data <- data.frame(
level1="CEO",
level2=c( rep("boss1",4), rep("boss2",4)),
level3=paste0("mister_", letters[1:8])
)
# transform it to a edge list!
edges_level1_2 <- data %>% select(
level1, level2) %>% unique %>% rename(
from=level1, to=level2)
edges_level2_3 <- data %>% select(
level2, level3) %>% unique %>% rename(
from=level2, to=level3)
edge_list=rbind(edges_level1_2, edges_level2_3)
# plot
graph_Data <- graph_from_data_frame( edge_list )
ggraph(graph_Data, layout = 'dendrogram', circular = TRUE) +
geom_edge_diagonal()+
geom_edge_diagonal() +
geom_node_point() +
theme_void()
Output:
Edge style Dendrogram
To make the straight edge dendrogram we will use geom_edge_diagonal() methods.
# libraries
library(ggraph)
library(igraph)
library(tidyverse)
# create a data frame
data <- data.frame(
level1="CEO",
level2=c( rep("boss1",4), rep("boss2",4)),
level3=paste0("mister_", letters[1:8])
)
# transform it to a edge list!
edges_level1_2 <- data %>% select(
level1, level2) %>% unique %>% rename(
from=level1, to=level2)
edges_level2_3 <- data %>% select(
level2, level3) %>% unique %>% rename(
from=level2, to=level3)
edge_list=rbind(edges_level1_2, edges_level2_3)
# Now we can plot that
graph_Data <- graph_from_data_frame( edge_list )
ggraph(graph_Data, layout = 'dendrogram') +
geom_edge_link()+
geom_node_point() +
theme_void()
Output:
Labels in Dendrogram
To add the labels into the dendrogram we will use geom_node_text() which will add the labels into the graph into a hierarchical structure
# libraries
library(ggraph)
library(igraph)
library(tidyverse)
# create a data frame
data <- data.frame(
level1="CEO",
level2=c( rep("boss1",4), rep("boss2",4)),
level3=paste0("mister_", letters[1:8])
)
# transform it to a edge list!
edges_level1_2 <- data %>% select(
level1, level2) %>% unique %>% rename(
from=level1, to=level2)
edges_level2_3 <- data %>% select(
level2, level3) %>% unique %>% rename(
from=level2, to=level3)
edge_list=rbind(edges_level1_2, edges_level2_3)
# Now we can plot that
graph_Data <- graph_from_data_frame( edge_list )
ggraph(graph_Data, layout = 'dendrogram') +
geom_edge_diagonal() +
geom_node_text(aes( label=name)) +
theme_void()
Output:
Customize Labels in Dendrogram
To Customize Labels in Dendrogram we use geom_node_text() which will add the labels along with color into the graph into the hierarchical structure
# libraries
library(ggraph)
library(igraph)
library(tidyverse)
# create a data frame
data <- data.frame(
level1="CEO",
level2=c( rep("boss1",4), rep("boss2",4)),
level3=paste0("mister_", letters[1:8])
)
# transform it to a edge list!
edges_level1_2 <- data %>% select(
level1, level2) %>% unique %>% rename(
from=level1, to=level2)
edges_level2_3 <- data %>% select(
level2, level3) %>% unique %>% rename(
from=level2, to=level3)
edge_list=rbind(edges_level1_2, edges_level2_3)
# Now we can plot that
graph_Data <- graph_from_data_frame( edge_list )
ggraph(graph_Data, layout = 'dendrogram') +
geom_edge_diagonal() +
geom_node_text(aes( label=name, color="red")) +
theme_void()
Output:
Customize Nodes in Dendrogram
To Customize Labels in Dendrogram we use geom_node_point() which will add the nodes along with color into the graph into a hierarchical structure
# libraries
library(ggraph)
library(igraph)
library(tidyverse)
# create a data frame
data <- data.frame(
level1="CEO",
level2=c( rep("boss1",4), rep("boss2",4)),
level3=paste0("mister_", letters[1:8])
)
# transform it to a edge list!
edges_level1_2 <- data %>% select(
level1, level2) %>% unique %>% rename(
from=level1, to=level2)
edges_level2_3 <- data %>% select(
level2, level3) %>% unique %>% rename(
from=level2, to=level3)
edge_list=rbind(edges_level1_2, edges_level2_3)
# Now we can plot that
graph_Data <- graph_from_data_frame( edge_list )
ggraph(graph_Data, layout = 'dendrogram') +
geom_edge_diagonal() +
geom_node_text(aes( label=name, color="red")) +
geom_node_point(aes(color ="Blue"))+
theme_void()
Output:
