I have a dataset like these (df):

I created a ggplot like this code which show the student body by age

ggplot(df, aes(x=Age, y=n))   
      geom_bar(stat="identity")   ggtitle("Student Body by Age at ETH in the assesment year")   scale_y_continuous(labels = function(x) format(x, scientific = FALSE))

Now I would like to create a legend next to the histogram which show the successful rate of the assesment year by Age. With these dataset

Is there a code where I can add a legend with the success rate of age?

The Histogram is fine, but I want a legend which show the successful rate by age in the right side.

CodePudding user response：

What you are describing isn't really a legend in the ggplot sense, but can be achieved by adding a table where the legend would normally be. Using the same data names as @langtang, we can do:

library(ggpubr)
library(patchwork)

ggplot(df, aes(x=Age, y=n))   
  geom_bar(stat="identity")   
  ggtitle("Student Body by Age at ETH in the assesment year")   
  scale_y_continuous(labels = function(x) format(x, scientific = FALSE))  
  ggtexttable(success_rates, rows = NULL, theme = ttheme("light"))  
  plot_layout(widths = 2:1)

^{Created on 2022-07-31 by the}

CodePudding user response：

You can create a custom legend (actually another ggplot plot) and add both using patchwork and also do some customization to make it good.

library(tidyverse)
library(patchwork)

df <- data.frame(
  Age = c(18, 19, 20, 21, 23, 24, 25),
  n = c(2500L, 1200L, 4500L, 800L, 120L, 50L, 100L)
)

pc_data <- data.frame(
  stringsAsFactors = FALSE,
  Age = c("18-19", "20-21", "23-24", "25 "),
  success = c(80, 60, 50, 20)
)


p1 <- ggplot(df, aes(x=Age, y=n))   
  geom_bar(stat="identity")  
  scale_y_continuous(labels = function(x) format(x, scientific = FALSE))  
  scale_x_continuous(labels = 18:25, breaks = 18:25)  
  labs(y = NULL)  
  theme_bw()  
  theme(
    panel.grid.minor = element_blank(),
    panel.grid.major.x = element_blank()
  )
  
  
p2 <- pc_data %>% 
  mutate(
    Age = fct_rev(factor(Age))
  ) %>% 
  ggplot(aes(Age, success))  
  geom_col(fill = colorspace::lighten("gray"), width = 0.7)  
  coord_flip()  
  labs( x = NULL, y = NULL, 
        title = "Success rate\nof Age")  
  geom_text(aes(Age, success, label = paste0(success, "%")), 
            size = 4, hjust = 1)  
  theme_classic()  
  theme(
    axis.line = element_blank(),
    axis.text.y = element_text(size = 9, angle = 90, hjust = 0.5),
    axis.ticks = element_blank(),
    axis.text.x = element_blank(),
    plot.title = element_text(color = colorspace::lighten("black", amount = 0.5))
  )

layout <- "
AAAA##
AAAABB
"

p1   p2    plot_layout(design = layout, heights = c(1, 30))  
  plot_annotation(
    title = "Student Body by Age at ETH in the assesment year"
  )