Change standard error color for geom_smooth

Question

I'm plotting some data using geom_smooth and looking for a way to change the color of the standard error shading for each line to match that line (ie., a red line would have it's standard error shaded red).

I've looked through the official ggplot2 documentation as well as the list of opts() at https://github.com/hadley/ggplot2/wiki/%2Bopts%28%29-List.

Any advice (or just confirmation of whether or not it's possible) is appreciated.

Answer 1

Your (understandable) mistake is to think that you should be changing the color rather than the fill. The standard error shadings are made with geom_ribbon essentially, and they are a 2d area, so the "color" they are "filled" with is determined by fill, not colour.

Try:

geom_smooth(aes(...,fill = variable)) 

where variable is the same one you map to colour elsewhere.

Answer 2

If you have multiple groups you simple define color = Vars and group = Vars within ggplot(aes()), and then additional aes(fill = Vars) within geom_smooth(aes(fill = Species)). (Based on answer here)

Dummy example:

# Make confidence intervals the same color as line by group ggplot(iris, aes(x = Sepal.Length,                   y = Sepal.Width,                   group = Species,                  color = Species)) +    geom_point() +    geom_smooth(aes(fill = Species))  # additional `aes()` referencing to confidence interval as a `fill` not as a `color`