Boxplot, how to match outliers' color to fill aesthetics?

Question

I am trying to match boxplot\'s outliers color to the fill color which is set by aesthetic (scale_colour_discrete).

Here is an example.

m <- ggplo         


        

Answer 1

As @koshke said, having the outliers colored like the lines of the box (not the fill color) is now easily possible by setting outlier.colour = NULL:

m <- ggplot(movies, aes(y = votes, x = factor(round(rating)),
    colour = factor(Animation)))
m + geom_boxplot(outlier.colour = NULL) + scale_y_log10()

• outlier.colour must be written with "ou"
• outlier.colour must be outside aes ()

I'm posting this as a late answer because I find myself looking this up again and again, and I also posted it for the related question Coloring boxplot outlier points in ggplot2?.

Answer 2

I had a very similar issue. I wanted to match style with a previous plot, so wanted black borders with coloured fill, and matching outliers.

My solution was to over-print , once with colour= and the default solid circle point, and once with fill= and an open circle point-shape

p <- ggplot(mtcars, aes(factor(cyl), mpg))
p + geom_boxplot(aes(colour=factor(cyl))) + 
    geom_boxplot(aes(fill=factor(cyl)), outlier.shape=21)

boxplot with coloured fill, and black borders and median line

Answer 3

I found a solution to the fact that setting geom_boxplot(outlier.colour = NULL) doesn't work anymore in newest versions of R (@jonsnow speaks about version 1.0.0 of ggplot2).

In order to replicate the behaviour that @cbeleites propsed you simply need to use the following code:

update_geom_defaults("point", list(colour = NULL))
m <- ggplot(movies, aes(y = votes, x = factor(round(rating)),
            colour = factor(Animation)))
m + geom_boxplot() + scale_y_log10()

as expected this produces plot with points that match the line color.

Of course one should remember to restore the default if he needs to draw multiple plots:

update_geom_defaults("point", list(colour = "black"))

The solution was found by reading the ggplot2 changelog on github:

The outliers of geom_boxplot() use the default colour, size and shape from geom_point(). Changing the defaults of geom_point() with update_geom_defaults() will apply the same changes to the outliers of geom_boxplot(). Changing the defaults for the outliers was previously not possible. (@ThierryO, #757)

Posted here as well: Coloring boxplot outlier points in ggplot2?

Answer 4

I found a way to do this, editing raw grid object.

library(ggplot2)

match.ol.col <- function(plt,aes.cp='fill') {
  # matches outliers' color to either fill or colour aesthetics
  #   plt: ggplot layer object having boxplot
  #   aes.cp: aetsthetic from which copy color.  must be either 'fill' or 'col'
  # returns grid objects, so print it wigh grid.draw(), not print()
  if (aes.cp %in% c('color', 'colour')) aes.cp <- 'col'
  grob <- ggplotGrob(plt)
  bps <- getGrob(grob, 'boxplots', grep=T)
  for (bp in bps$children) {
    p <- getGrob(bp, 'point', grep=T)
    if (is.null(p)) next
    r <- getGrob(bp, 'rect', grep=T)
    grob <- geditGrob(grob, p$name, gp=gpar(col=r$gp[[aes.cp]]))
  }
  return(grob)
}


m <- ggplot(movies, aes(y = votes, x = factor(round(rating)),
    colour=factor(Animation)))
p <- m + geom_boxplot() + scale_y_log10()

grob <- match.ol.col(p, aes.cp='colour')
grid.draw(grob)

results: