Pheatmap question, how to draw a heatmap with pheatmap when you have 200 DEG to show on the heatmap?

Question

[soheilazareie]

I have 200 differentially expressed genes in my RNAseq dataset and I want to have them all on my heatmap, however, because they are a lot (200), I am not able to see them on heatmap clearly, how I can figure out the size of a heatmap which covers 200 or more genes on one heatmap, how big it should be sized?

Thanks,

[cpad0112]

May be you can use discrete colors instead of continuous colors and breaks @OP

Answer 1

[Kevin Blighe]

You can either modify the cex parameter, or, preferably, modify the dimensions of your output figure, or use a combination of these:

Create random data of dimensions 200 x 25

data <- replicate(25, rnorm(200))
rownames(data) <- paste("Gene", c(1:nrow(data)))
colnames(data) <- paste("Sample", c(1:ncol(data)))

dim(data)
[1] 200  25

Modify cex and output dimensions

pdf("pheatmap.pdf", width=5, height=12)
  out <- pheatmap(data, 
      show_rownames=T,
      cluster_cols=T,
      cluster_rows=T,
      scale="row",
      clustering_distance_rows="euclidean",
      clustering_distance_cols="euclidean",
      clustering_method="complete",
      border_color=FALSE,
      cex=0.7)
dev.off()

-------------------------------------

Just be aware that, with that many genes, it will always be a struggle to get it exactly as you'd want it, e.g., for a publication.

Kevin

[soheilazareie]

Hi Kevin, Thanks so much for your reply. But I am a bit confused when we create a random data of dimensions,(data <- replicate(25, rnorm(200)) rownames(data) <- paste("Gene", c(1:nrow(data))) colnames(data) <- paste("Sample", c(1:ncol(data)))

dim(data)), in this code, where should I include my own data that I am supposed to make a heat map? also, is this code* separate or should be used after the above one, pdf("pheatmap.pdf", width=5, height=12) *out <- pheatmap(data, show_rownames=T, cluster_cols=T, cluster_rows=T, scale="row", clustering_distance_rows="euclidean", clustering_distance_cols="euclidean", clustering_method="complete", border_color=FALSE, cex=0.7) dev.off(),

another question, I have been trying to use your code but I dont know where my pdf is going to be saved in, and when I run this code with my own data, the only thing I get is , "pdf 5 " Thanks again, Soheila

[Kevin Blighe]

To know the location where the PDF will be saved, simply run this command:

getwd()

You can change the directory with:

setwd("/home/kblighe/results/")

In the code example that I have given, your data would be used in place of my object called data.

The only parameters that I have encouraged you to use in your own code are:

• pdf() with width and height specified
• pheatmap() with cex specified

You do not need to worry about any of the other parameters that I have used.

Trust this helps!

[soheilazareie]

perfect, it worked, thanks so much!

Best, Soheila

[Kevin Blighe]

Good work!