How can I control the error bar colors to be the same as geom_point colors?

January 12, 2023

I wanted to make a point plot in ggplot and I used geom_point function to do it. To colorize the points, I used levels to fill them either in red or blue. However, now I’m adding the error bars to my point plot with geom_errorbar function, it seems I can’t give the colors I used in geom_points. In other words, I can only give them one color, which is by default black. Is there any way I can control the color of the error bars?

Let’s say we have the following data frame:

df <- data.frame (Xvalue=c(1.2, 1.3, 2.1, 2.4, 2.7),
                 Yvalue=c(12, 15, 17, 24, 27),
                 Kind=c('A', 'B', 'A', 'B', 'B'),
                 Ymax=c(13, 16, 19, 26, 29),
                 Ymin=c(11, 14, 15, 22, 25))
df$Kind = factor(df$Kind)

Now I want to draw the plot with the error bars:

myplot <- ggplot (df, aes(Xvalue, Yvalue, fill=Kind)) + 
  geom_point( shape=21, size= 4, alpha= 0.7)+
  geom_errorbar(aes(ymin=Ymin, ymax=Ymax,  width=0.08))
myplot

This results in a plot with error bars of black. How can I make sure this is the same color as the points?

Bonus question: Is this how you would usually make two colors in your points, I mean by putting the "levels" in the ggplot function as fill? Do you have an alternative way to where one doesn’t need to use Shape=21, where the outer pirameter of the circle is black?

Bonus qeustion 2: Is it generally easier to plot two kinds of points, when they are in 1 dataframe, or is it better to seperate the dataframes? For instance, I can have a smaller dataframe for the Kind A, and another one for dataframe B. Would that make the life easier? Why I’m asking is that, when I tried to plot with more than one levels (for instance once "Kind" and the other one "Original country"), it was quite confusing to plot points in different colors and sizes.

>Solution :

You should add the color aes to your geom_errorbar like this (Please note: you could add show.legend FALSE to your geom_errorbar so there is no line in your elements of your legend):

library(ggplot2)
myplot <- ggplot (df, aes(Xvalue, Yvalue, fill=Kind)) + 
  geom_point( shape=21, size= 4, alpha= 0.7)+
  geom_errorbar(aes(ymin=Ymin, ymax=Ymax, width=0.08, color = Kind), show.legend = FALSE)
myplot