Making a heatmap is an essential skill for a bioinformatician. Just check how many figures are heatmap or heatmap variants in the genomics or single cell paper.
But you probably do not understand heatmap. 7 reading resources to understand heatmap!
1/ Mapping quantitative data to color https://www.nature.com/articles/nmeth.2134
2/ Heat map from Nature Method column https://www.nature.com/articles/nmeth.1902
3/ A tale of two heatmap functions https://rpubs.com/crazyhottommy/a-tale-of-two-heatmap-functions An old post by me.
4/ Heatmap demystified https://rpubs.com/crazyhottommy/heatmap_demystified yet another post by me
5/ understand color mapping is key https://jokergoo.github.io/ComplexHeatmap-reference/book/a-single-heatmap.html#colors
6/ understand rastering https://jokergoo.github.io/2020/06/30/rasterization-in-complexheatmap/
7/ what happens when you have a huge matrix 20,000 rows/genes x 50 columns to plot? https://gdevailly.netlify.app/post/plotting-big-matrices-in-r/
I learned so much from Zuguang Gu, thanks for his awesome Complexheatmap package https://jokergoo.github.io/ComplexHeatmap-reference/book/index.html . it is my go-to tool for making heatmaps.