ggdendro

This is a set of tools for creating dendrograms and tree plots using ggplot in [R]

Important functions

ggdendro offers a generic function to extract data and text from the various clustering models:

• dendro_data() extracts cluster information from the model object, e.g. cluster allocation, line segment data or label data.

dendro_data has methods for the following classes:

• tree
• hclust
• dendrogram

These methods create an object of class "dendro", which is essentially a list of data.frames. To extract the relevant data frames from the list, use the three accessor functions:

• segment for the line segment data
• label for the text for each end segment
• leaf_label for the leaf labels of a tree diagram

The results of these functions can then be passed to ggplot() for plotting.

Example

library(ggplot2)
library(ggdendro)
hc <- hclust(dist(USArrests), "ave")
hcdata <- dendro_data(hc, type="rectangle")
ggplot() + 
    geom_segment(data=segment(hcdata), aes(x=x, y=y, xend=xend, yend=yend)) +
    geom_text(data=label(hcdata), aes(x=x, y=y, label=label, hjust=0), size=3) +
    coord_flip() + scale_y_reverse(expand=c(0.2, 0))
    
### demonstrate plotting directly from object class hclust
ggdendrogram(hc, rotate=FALSE)
ggdendrogram(hc, rotate=TRUE)
### demonstrate converting hclust to dendro using dendro_data first
hcdata <- dendro_data(hc)
ggdendrogram(hcdata, rotate=TRUE) + labs(title="Dendrogram in ggplot2")