A heat map (or heatmap) is a graphical representation of data where the individual values contained in a matrix are represented as colors. It is a bit like looking a data table from above. It is really useful to display a general view of numerical data,
not to extract specific data point. It is quite straight forward to make a heat map, as shown on the examples below. However be careful to understand the underlying mechanisms. You will probably need to normalise your matrix, choose
a relevant colour palette, use cluster analysis and thus permute the rows and the columns of the matrix to place similar values near each other according to the clustering.