Given:
x <- as.matrix(mtcars)
One can use heatmap.2 - a more recent optimized version of heatmap, by loading the following library:
require(gplots)
heatmap.2(x)
To add a title, x- or y-label to your heatmap, you need to set the main, xlab and ylab:
heatmap.2(x, main = "My main t...