Added color by group

Question

Hi everyone! I try combined boxplot and stripchart to represent some data, and trying to color by group:

xfact yvar Non-response 0.0012 Non-response 0.0002 Non-response 0.0018 Non-response 0.0004 Non-response 0.0013 Non-response 0.0004 Non-response 0.0029 Non-response 0.0016 Response 0.0177 Response 0.0335 Response 0.0118 Response 0.0309 Response 0.0314 Response 0.0135

That my code:

boxplot(yvar~xfact, data = my.data, ylab= "CD8/GAPDH relative expression", 
names = c("Non-response n=14", "Response n=6"), outpch =NA)  
stripchart(yvar~xfact, data = my.data, vertical = TRUE, method = 
"overplot", pch = 21, col = "black", bg = c("green", "red"), add= TRUE) 

So I expect colored green for non-response and red for response, instead I have some weird output: my output

So can your help me to color by group(non-response and response) not randomly?

Answer 1

This is not really a solution, only a work-around.

Assigning a color (col) by group works, so you could use

boxplot(yvar~xfact, data = my.data, ylab= "CD8/GAPDH relative expression", 
    names = c("Non-response n=14", "Response n=6"), outpch =NA)  
stripchart(yvar~xfact, data = my.data, vertical = TRUE, 
    method = "overplot", pch = 16, col = c("green", "red"), add = T) 

If you really want to get the appearance of a circle with a border, you can add the border separately.

boxplot(yvar~xfact, data = my.data, ylab= "CD8/GAPDH relative expression", 
    names = c("Non-response n=14", "Response n=6"), outpch =NA)  
stripchart(yvar~xfact, data = my.data, vertical = TRUE, 
    method = "overplot", pch = 16, col = c("green", "red"), add = T) 
stripchart(yvar~xfact, data = my.data, vertical = TRUE, 
    method = "overplot", pch = 21, col="black", add = T)