I am trying to know gene names from a heatmap made by heatmap. 2. Since I have many genes, the gene names (row labels) are not readable. I typed following. Please teach me how to know gene names from heatmap.

data <- read.table("sample.txt") data <- as.matrix(data) out_f <- "cluster2.png"

library(gplots)

heatmap.2( data, scale = "row", dendrogram = "both", Rowv = TRUE, Colv = TRUE, trace = "none", main = "Density none" 
)