Plot heatmap

To visualize the (DE) genes, we want to plot a heatmap. To do so, we can use the function aheatmap() from the library NMF.

The variable mostDE from Exercise 11 is available for you in your workspace.

100 XP

Load NMF.
Subset sce to keep only the 20 most variable genes. Extract the normalized log counts from the object sce subsetted to these genes and assign it to the variable norm.
Transform norm to a matrix. Assign it to the variable mat.
Plot a heatmap of the object mat.