ggpairs, color by group but single regression line-CodePudding

Given the following ggpairs plotting:

data(iris)
ggpairs(iris[1:4],
        lower=list(
          mapping = aes(color=iris$Species),
          continuous = wrap("points", size=0.7)
          )
        )

Which results in:

How can I add single regression lines to each of the scatter plots without the regression line also being mapped to the grouping as would occur when adding continuous = wrap("smooth")?

I would like the points to be colored by group but the regression line for the relationship between the x and y variable overall.

I can't figure out where to place the aes mapping so that it only affects 'points' and not 'smooth'.

CodePudding user response：

You need to create your own function if you want specialized plots like this. It must be in a particular format, taking a data, mapping and ... argument, and create a ggplot from these:

library(GGally)

my_func <- function(data, mapping, ...) {
  
    ggplot(data, mapping)   
      geom_point(size = 0.7)  
      geom_smooth(formula = y~x, method = loess, color = "black")
  }

ggpairs(iris[1:4],
        lower=list(
          mapping = aes(color=iris$Species),
          continuous = my_func
          )
        )

If you are looking for a straight regression line, then just modify my_func as appropriate. For example,

my_func <- function(data, mapping, ...) {
  
    ggplot(data, mapping)   
      geom_point(size = 0.7)  
      geom_smooth(formula = y~x, method = lm, color = "black", se = FALSE,
                  linetype = 2)
  }

Gives you: