How to use loess method in GGally::ggpairs using wrap function

Question

I am trying to replicate this simple example given in the Coursera R Regression Models course:

require(datasets)
data(swiss)
require(GGally)
require(ggplot2)
ggpairs(swiss, lower = list(continuous = "smooth", params = c(method = "loess")))

I expect to see a 6x6 pairs plot - one scatterplot with loess smoother and confidence intervals for each combination of the 6 variables in the swiss data.

However, I get the following error:

Error in display_param_error() : 'params' is a deprecated argument. Please 'wrap' the function to supply arguments. help("wrap", package = "GGally")

I looked through the ggpairs() and wrap() help files and have tried lots of permutations of the wrap() and wrap_fn_with_param_arg() functions.

I can get this to work as expected:

ggpairs(swiss, lower = list(continuous = wrap("smooth")))

But once I add the loess part in, it does not:

ggpairs(swiss, lower = list(continuous = wrap("smooth"), method = wrap("loess")))

I get this error when I tried the line above.

Error in value[3L] : The following ggpair plot functions are readily available: continuous: c('points', 'smooth', 'density', 'cor', 'blank') combo: c('box', 'dot', 'facethist', 'facetdensity', 'denstrip', 'blank') discrete: c('ratio', 'facetbar', 'blank') na: c('na', 'blank')

diag continuous: c('densityDiag', 'barDiag', 'blankDiag') diag discrete: c('barDiag', 'blankDiag') diag na: c('naDiag', 'blankDiag')

You may also provide your own function that follows the api of function(data, mapping, ...){ . . . } and returns a ggplot2 plot object Ex: my_fn <- function(data, mapping, ...){ p <- ggplot(data = data, mapping = mapping) + geom_point(...) p } ggpairs(data, lower = list(continuous = my_fn))

Function provided: loess

Obviously I am entering loess in the wrong place. Can anyone help me understand how to add the loess part in?

Note that my problem is different to this one, as I am asking how to implement loess in ggpairs since the params argument became deprecated.

Thanks very much.

Answer 1

One quick way is to write your own function... the one below was edited from the one provided by the ggpairs error message in your question

library(GGally)
library(ggplot2)    
data(swiss)

# Function to return points and geom_smooth
# allow for the method to be changed
my_fn <- function(data, mapping, method="loess", ...){
      p <- ggplot(data = data, mapping = mapping) + 
      geom_point() + 
      geom_smooth(method=method, ...)
      p
    }

# Default loess curve    
ggpairs(swiss[1:4], lower = list(continuous = my_fn))

# Use wrap to add further arguments; change method to lm
ggpairs(swiss[1:4], lower = list(continuous = wrap(my_fn, method="lm")))

---

This perhaps gives a bit more control over the arguments that are passed to each geon_

  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"))))