Fill in ggplot2 is always red, regardless of what colour is actually specified.

[a-hurst]

For whatever reason, whenever I try to specify a fill colour for a violin plot it always renders as a pastel red, regardless of what I tell it. Here is some simple code that reproduces the bug for me in a fresh R session:

library(ggplot2)

blah <- rnorm(2000, 3, 1.5)
blah2 <- rep("test", times=2000)
df = data.frame(a = blah2, b = blah)
ggplot(data = df) + geom_violin(aes(x = a, y = b, fill="grey80"))

Running this code gives me this:

This happens no matter which fill colour I specify. When I don't specify a fill, the fill defaults to white as expected:

This happens with the official CRAN binary in the R GUI.app as well as with R 3.3.1 installed from Homebrew. I also did a fresh install of ggplot2 on a fresh install of R when I generated the above graphs. Any ideas what's going on?

Platform info:

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-apple-darwin13.4.0 (64-bit)

[jac0bean9]

You need fill to be outside aes, i.e..:

`library(ggplot2)

blah <- rnorm(2000, 3, 1.5)
blah2 <- rep("test", times=2000)
df = data.frame(a = blah2, b = blah)
ggplot(data = df) + geom_violin(fill="grey80", aes(x = a, y = b))`

[a-hurst]

Thanks, it works properly now! Any reason it defaults to that red instead of throwing an error or something if it's defined within aes()? Had it thrown an error I would have been much less bewildered.

[steveharoz]

By putting the values in aes, you're basically generating a new factor variable and a legend.

ggplot(mtcars)+
    geom_point(aes(x = mpg, y = wt, color = 'blah'))+
    geom_point(aes(x = mpg, y = drat, color = 'asdfasdf'))+
    scale_color_manual(values = c('blah' = 'blue', 'asdfasdf' = 'red'))

Notice the legend.

If you set the values outside of aes, ggplot2 won't make the legend for you.

ggplot(mtcars)+
  geom_point(aes(x = mpg, y = wt), color = 'blue')+
  geom_point(aes(x = mpg, y = drat), color = 'red')

[a-hurst]

Ah, that makes perfect sense. Thanks again for your help!

[ipstone]

Might I ask why it makes sense? I am new to ggplot, using qplot, somehow my fill color is always red. what is wrong with qplot(x, y, color='blue'...), why is it always 'red'?

[has2k1]

@ipstone, if you are new to ggplot2 stay away from qplot.

Might I ask why it makes sense?

The aesthetic values in aes() are data which is properly fit to a scale, hence it must be interpreted with a guide/legend. Aesthetic values outside aes() are direct settings which by-pass the scaling mechanism hence no need for a guide/legend.

[lock]

This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/