How to get member of clusters from R's hclust/heatmap.2

Question

I have the following code that perform hiearchical clustering and plot them in heatmap.

library(gplots)
set.seed(538)
# generate data
y <- matrix(rnorm(50), 10, 5, dimnames=list(paste("g", 1:10, sep=""), paste("t", 1:5, sep="")))
# the actual data is much larger that the above

# perform hiearchical clustering and plot heatmap
test <- heatmap.2(y)

Which plot this:

What I want to do is to get the cluster member from each hierarchy of in the plot yielding:

Clust 1: g3-g2-g4
Clust 2: g2-g4
Clust 3: g4-g7
etc
Cluster last: g1-g2-g3-g4-g5-g6-g7-g8-g9-g10

Is there a way to do it?

Answer 1

I did have the answer, after all! @zkurtz identified the problem ... the data I was using were different than the data you were using. I added a set.seed(538) statement to your code to stabilize the data.

Use this code to create a matrix of cluster membership for the dendrogram of the rows using the following code:

cutree(as.hclust(test$rowDendrogram), 1:dim(y)[1])

This will give you:

    1 2 3 4 5 6 7 8 9 10
g1  1 1 1 1 1 1 1 1 1  1
g2  1 2 2 2 2 2 2 2 2  2
g3  1 2 2 3 3 3 3 3 3  3
g4  1 2 2 2 2 2 2 2 2  4
g5  1 1 1 1 1 1 1 4 4  5
g6  1 2 3 4 4 4 4 5 5  6
g7  1 2 2 2 2 5 5 6 6  7
g8  1 2 3 4 5 6 6 7 7  8
g9  1 2 3 4 4 4 7 8 8  9
g10 1 2 3 4 5 6 6 7 9 10