Change colors in ggpairs now that params is deprecated

Question

I saw these posts GGally::ggpairs plot without gridlines when plotting correlation coefficient use ggpairs to create this plot

After reading I was able to implement this hack https://github.com/tonytonov/ggally/blob/master/R/gg-plots.r and my plot looks like this

I think this is a good result but I cannot change the colors.

A MWE is this

library(ggally)

# load the hack
source("ggally_mod.R") 
# I saved https://github.com/tonytonov/ggally/blob/master/R/gg-plots.r as "ggally_mod.R"
assignInNamespace("ggally_cor", ggally_cor, "GGally")

ggpairs(swiss)

Now I want to run

ggpairs(swiss, 
 lower=list(continuous="smooth", wrap=c(colour="blue")),
 diag=list(continuous="bar", wrap=c(colour="blue")))

But the colours remain the same. Is there a way to change the colours now that params is not working anymore?

Answer 1

You are not using wrap correctly - see the vignette for details. Also for the diagonal you now have to use the function barDiag (but ggpairs gives very helpful errors to tell this)

So for your example, we can change the colour of the points in the lower panels and the fill of the bars below

library(GGally)
library(ggplot2)
ggpairs(swiss[1:3], 
        lower=list(continuous=wrap("smooth", colour="blue")),
        diag=list(continuous=wrap("barDiag", fill="blue")))

However, as the colour of the smooth is hard coded (see ggally_smooth), to change its colour you need to define you own function to pass. So from here

my_fn <- function(data, mapping, pts=list(), smt=list(), ...){
              ggplot(data = data, mapping = mapping, ...) + 
                         do.call(geom_point, pts) +
                         do.call(geom_smooth, smt) 
                 }

# Plot 
ggpairs(swiss[1:4], 
        lower = list(continuous = 
                       wrap(my_fn,
                            pts=list(size=2, colour="red"), 
                            smt=list(method="lm", se=F, size=5, colour="blue"))),
                     diag=list(continuous=wrap("barDiag", fill="blue")))

---

In a similar way, here is a way to define a new upper correlation function (similar to what you have)

cor_fun <- function(data, mapping, method="pearson", ndp=2, sz=5, stars=TRUE, ...){

    x <- eval_data_col(data, mapping$x)
    y <- eval_data_col(data, mapping$y)

    corr <- cor.test(x, y, method=method)
    est <- corr$estimate
    lb.size <- sz* abs(est) 

    if(stars){
      stars <- c("***", "**", "*", "")[findInterval(corr$p.value, c(0, 0.001, 0.01, 0.05, 1))]
      lbl <- paste0(round(est, ndp), stars)
    }else{
      lbl <- round(est, ndp)
    }

    ggplot(data=data, mapping=mapping) + 
      annotate("text", x=mean(x, na.rm=TRUE), y=mean(y, na.rm=TRUE), label=lbl, size=lb.size,...)+
      theme(panel.grid = element_blank())
  }


ggpairs(swiss, 
        lower=list(continuous=wrap("smooth", colour="blue")),
        diag=list(continuous=wrap("barDiag", fill="blue")),
        upper=list(continuous=cor_fun))