CODEWITHSUNDEEP
rggplot2density-plot
Michael
Michael

Reputation: 35

Add custom legend of mean/mode values to ggplot density plot

I am trying to add a legend to a density plot generated via ggplot2, but instead of adding sample labels, I am trying to fill the legend with numbers.

library(ggplot2)
library(modeest)

set.seed(9)
d1=as.data.frame(rnorm(1000,mean=0.33,sd=0.138))
names(d1)=c("value")
mean_d1=mean(d1$value)                    #Mean=0.33081
mode_d1=mlv(d1$value,method="shorth")[1]  #Mode=0.35191

gg=ggplot(d1,aes(value))
gg +
geom_density()

This makes a graph like this: enter image description here

Is there a way to add a legend (embedded in the upper right corner) which contains the mean and mode values I have already calculate?

Upvotes: 1

Views: 1890

Answers (1)

M--
M--

Reputation: 28955

You can add text to ggplot using annotate:

 p + annotate("text", x = 0.6, y = 3, label = paste ("Mean ==", mean_d1), parse = TRUE) +
     annotate("text", x = 0.6, y = 2.8, label = paste ("Mode ==", mode_d1), parse = TRUE)

Update:

If you want to use this for different plots then look below;

max_y <- ggplot_build(gg)$layout$panel_ranges[[1]]$y.range[2]
max_x <- ggplot_build(gg)$layout$panel_ranges[[1]]$x.range[2]

gg + 
    annotate("text", x = max_x * 0.85, y = max_y * 0.95, label = paste 
                   ("Mean ==", round(mean_d1, digits=3)), parse = TRUE) +
    annotate("text", x = max_x * 0.85, y = max_y * 0.9, label = paste 
                   ("Mode ==", round(as.numeric(mode_d1), digits=3)), parse = TRUE)

Upvotes: 1

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