CODEWITHSUNDEEP
rclassificationhierarchical-clusteringdendrogramdendextend
borgr
borgr

Reputation: 25305

How to color branches in R dendogram as a function of the classes in it?

I wish to visualize how well a clustering algorithm is doing (with certain distance metric). I have samples and their corresponding classes. To visualize, I cluster and I wish to color the branches of a dendrogram by the items in the cluster. The color will be the color most items in the hierarchical cluster correspond to (given by the data\classes).

Example: If my clustering algorithm chose indexes 1,21,24 to be a certain cluster (at a certain level) and I have a csv file containing a class number in each row corresponding to lets say 1,2,1. I want this edge to be coloured 1.

Example Code:

require(cluster)
suppressPackageStartupMessages(library(dendextend))
dir <- 'distance_metrics/'
filename <- 'aligned.csv'
my.data <- read.csv(paste(dir, filename, sep=""), header = T, row.names = 1)
my.dist <- as.dist(my.data)
real.clusters <-read.csv("clusters", header = T, row.names = 1)
clustered <- diana(my.dist)
# dend <- colour_branches(???dend, max(real.clusters)???)
plot(dend)

EDIT: another example partial code

dir <- 'distance_metrics/' # csv in here contains a symmetric matrix
clust.dir <- "clusters/" #csv in here contains a column vector with classes
my.data <- read.csv(paste(dir, filename, sep=""), header = T, row.names = 1)
filename <- 'table.csv'
my.dist <- as.dist(my.data)
real.clusters <-read.csv(paste(clust.dir, filename, sep=""), header = T, row.names = 1)
clustered <- diana(my.dist)
dnd <- as.dendrogram(clustered)

Upvotes: 3

Views: 2050

Answers (3)

Tal Galili
Tal Galili

Reputation: 25306

The function you are looking for is color_brances from the dendextend R package, using the arguments clusters and col. Here is an example (based on Shaun Wilkinson's example):

library(cluster)
set.seed(999)
iris2 <- iris[sample(x = 1:150,size = 50,replace = F),]
clust <- diana(iris2)
dend <- as.dendrogram(clust)

temp_col <- c("red", "blue", "green")[as.numeric(iris2$Species)]
temp_col <- temp_col[order.dendrogram(dend)]
temp_col <- factor(temp_col, unique(temp_col))

library(dendextend)
dend %>% color_branches(clusters = as.numeric(temp_col), col = levels(temp_col)) %>% 
   set("labels_colors", as.character(temp_col)) %>% 
   plot

enter image description here

Upvotes: 1

Shaun Wilkinson
Shaun Wilkinson

Reputation: 473

Both node and edge color attributes can be set recursively on "dendrogram" objects (which are just deeply nested lists) using dendrapply. The cluster package also features an as.dendrogram method for "diana" class objects, so conversion between the object types is seamless. Using your diana clustering and borrowing some code from @Edvardoss iris example, you can create the colored dendrogram as follows: 

library(cluster)
set.seed(999)
iris2 <- iris[sample(x = 1:150,size = 50,replace = F),]
clust <- diana(iris2)
dnd <- as.dendrogram(clust)

## Duplicate rownames aren't allowed, so we need to set the "labels"
## attributes recursively. We also label inner nodes here. 
rectify_labels <- function(node, df){
  newlab <- df$Species[unlist(node, use.names = FALSE)]
  attr(node, "label") <- (newlab)
  return(node)
}
dnd <- dendrapply(dnd, rectify_labels, df = iris2)

## Create a color palette as a data.frame with one row for each spp
uniqspp <- as.character(unique(iris$Species))
colormap <- data.frame(Species = uniqspp, color = rainbow(n = length(uniqspp)))
colormap[, 2] <- c("red", "blue", "green")
colormap

## Now color the inner dendrogram edges
color_dendro <- function(node, colormap){
  if(is.leaf(node)){
    nodecol <- colormap$color[match(attr(node, "label"), colormap$Species)]
    attr(node, "nodePar") <- list(pch = NA, lab.col = nodecol)
    attr(node, "edgePar") <- list(col = nodecol)
  }else{
    spp <- attr(node, "label")
    dominantspp <- levels(spp)[which.max(tabulate(spp))]
    edgecol <- colormap$color[match(dominantspp, colormap$Species)]
    attr(node, "edgePar") <- list(col = edgecol)
  }
  return(node)
}
dnd <- dendrapply(dnd, color_dendro, colormap = colormap)

## Plot the dendrogram
plot(dnd)

enter image description here

Upvotes: 1

Edvardoss
Edvardoss

Reputation: 393

there are suspicions that misunderstood the question however I'll try to answer: from my previous objectives were rewritten by the example of iris

clrs <- rainbow(n = 3) # create palette
clrs <- clrs[iris$Species] # assign colors
plot(x = iris$Sepal.Length,y = iris$Sepal.Width,col=clrs) # simple test colors
# cluster
dt <- cbind(iris,clrs)
dt <- dt[sample(x = 1:150,size = 50,replace = F),] # create short dataset for visualization convenience
empty.labl <- gsub("."," ",dt$Species) # create a space vector with length of names intended for  reserve place to future text labels
dst <- dist(x = scale(dt[,1:4]),method = "manhattan")
hcl <- hclust(d = dst,method = "complete")
plot(hcl,hang=-1,cex=1,labels = empty.labl, xlab = NA,sub=NA)
dt <- dt[hcl$order,] # sort rows for  order objects in dendrogramm
text(x = seq(nrow(dt)), y=-.5,labels = dt$Species,srt=90,cex=.8,xpd=NA,adj=c(1,0.7),col=as.character(dt$clrs))

result

Upvotes: 0

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