1

About 18 months ago, this helpful exchange appeared, with code to show how to produce a plot of median along with interquartile ranges. Here's the code:

ggplot(data = diamonds) +
geom_pointrange(mapping = aes(x = cut, y = depth),
              stat = "summary",
              fun.ymin = function(z) {quantile(z,0.25)},
              fun.ymax = function(z) {quantile(z,0.75)},
              fun.y = median)

Producing this plot:

this plot

What I'd wonder is how to add labels for the median and IQ ranges, and how to format the bar (color, alpha, etc). I tried calling the plot as an object to see if there were objects within I could then use to call format functions, but nothing was obvious when I looked at it in the r Studio IDE.

Is this even doable? I know I can do a boxplot but that would have to include min/max. I'd like to produce boxplots with just mean/median and IQs.

Improve this question
4
  • You could just preprocess your data--calculate the descriptive stats you're using before plotting, and then use those numbers to make labels Commented Aug 14, 2018 at 22:24
  • 1
    Also with this: "how to format the bar (color, alpha, etc)" you'll have to be much more specific Commented Aug 14, 2018 at 22:25
  • Yes, I did a version where I coded the summary stats then manipulated a dataframe from there to plot. I was hoping to do it all within one ggplot call rather than multiple steps. Commented Aug 14, 2018 at 22:30
  • By format I mean...change the color of the bar, change the thickness, transparency. The typical things you can do in ggplot when you have objects to call. Commented Aug 14, 2018 at 22:31

1 Answer 1

Reset to default
1

You can change the formating like you would any ggplot layer, see the docs for Vertical intervals: lines, crossbars & errorbars in this case. An example of this is the following:

library(ggplot2)
ggplot(data = diamonds) +
  geom_pointrange(mapping = aes(x = cut, y = depth),
                  stat = "summary",
                  fun.ymin = function(z) {quantile(z,0.25)},
                  fun.ymax = function(z) {quantile(z,0.75)},
                  fun.y = median,
                  size = 4,             # <- adjusts size
                  colour = "red",       # <- adjusts colour
                  alpha = .3)           # <- adjusts transparency

enter image description here

If you want to control formatting for the points and lines individually you need to do as @camille suggests and pre-process your data as geom_pointrange() draws a single graphical object so the points and lines are one in the same.

I would suggest something like this:

library(dplyr)
library(ggplot2)

diamonds %>% 
  group_by(cut) %>% 
  summarise(median = median(depth),
            lq = quantile(depth, 0.25),
            uq = quantile(depth, 0.75)) %>% 

  ggplot(aes(cut, median)) +
  geom_linerange(aes(ymin=lq, ymax=uq), size = 4, colour = "blue", alpha = .4) +
  geom_point(size = 10, colour = "red", alpha = .8)

enter image description here

Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.