在ggplot2中的特定框上画一条对角线？

Question

Hi I am trying to draw diagonal lines on specific boxes which belongs to class2. I got this: Image1

My dataset:

---

samples genes   value   class
sample1 geneA   0.52    class2
sample1 geneB   1       class1
sample1 geneC   1       class1
sample2 geneD   1       class1
sample2 geneB   1       class1
sample2 geneH   0.4     class2
sample2 geneC   1       class1
sample3 geneE   0.44    class2
sample3 geneF   0.34    class2
sample3 geneB   1       class1
sample3 geneI   0.65    class2
sample3 geneC   1       class1
sample4 geneB   0.72    class2
sample4 geneC   0.41    class2
sample5 geneG   1       class1
sample5 geneB   1       class1
sample5 geneC   1       class1

---

Class1 is marked with yellow lines encircle the boxes. Can you please help me to figure out insert diagonal line on boxes belong to class2.

I want like this:

Image2

Thanks, kumarr

Answer 1

Here's one way to do it:

p <- ggplot(df, aes(x=genes,y=samples,fill=class)) + geom_tile()
p + geom_segment(
  aes(x=xmin,xend=xmax,y=ymin,yend=ymax), 
  subset(ggplot_build(p)$data[[1]],fill=="#00BFC4"),
  inherit.aes=F
)

with

library(ggplot2)
df <- read.table(header=T, text="samples genes   value   class
sample1 geneA   0.52    class2
sample1 geneB   1       class1
sample1 geneC   1       class1
sample2 geneD   1       class1
sample2 geneB   1       class1
sample2 geneH   0.4     class2
sample2 geneC   1       class1
sample3 geneE   0.44    class2
sample3 geneF   0.34    class2
sample3 geneB   1       class1
sample3 geneI   0.65    class2
sample3 geneC   1       class1
sample4 geneB   0.72    class2
sample4 geneC   0.41    class2
sample5 geneG   1       class1
sample5 geneB   1       class1
sample5 geneC   1       class1")