I have been using the R statistics package to display a heatmap of Illumina sequencing data (imported as a csv file of the sample names, species names, and the % abundance). I have managed to get all the way to displaying the heatmap and know how to change the colour scheme etc. I'm happy with how it looks but I would really like to have a colour key to indicate that red is a certain percentage range, and the same for orange and yellow. I've tried multiple ways of doing this but the main tutorials online are based on when you make a dendrogram within, should I do this?