I have the following data:

And I would like to plot the different blood parameters on the same plot with 2 different colors for the category placebo or test. Here is the code and what I have:

plot <- ggplot() 
  geom_line(data = file, aes(x = date, y = albumin, color = category))  
  geom_line( data = file, aes(x = date, y = protein, color = category))  
  scale_color_brewer(palette = "Set1")  
  theme_minimal(base_size = 16)
plot   xlab("Days at blood sampling")   ylab("Blood parameters")

My issue is to add a label with the name of each blood parameter next to each line, a bit like this:

How can I do this?

CodePudding user response：

One option to achieve your desired result would be "the secondary axis trick" which adds the labels as breaks and labels of a secondary y axis. To this end I first create a dataframe containing the values for the breaks (for which I chose the mean value) and the labels:

library(dplyr, warn = FALSE)
library(tidyr)
library(ggplot2)

breaks <- file |> 
  filter(date == max(date)) |> 
  summarise(across(c(albumin, protein), mean)) |> 
  tidyr::pivot_longer(cols = everything())
  
ggplot(file,aes(x = date)) 
  geom_line(aes(y = albumin, color = Category))  
  geom_line( aes(y = protein, color = Category))  
  scale_color_brewer(palette = "Set1")  
  scale_y_continuous(sec.axis = dup_axis(breaks = breaks$value, labels = stringr::str_to_title(breaks$name)), name = NULL)  
  theme_minimal(base_size = 16)  
  labs(x = "Days at blood sampling", y = "Blood parameters")

DATA

file <- data.frame(
  stringsAsFactors = FALSE,
          Category = c("placebo", "placebo", "placebo", "test", "test", "test"),
           albumin = c(2404, 2586, 2818, 2377, 2622, 2790),
           protein = c(6145, 5763, 6418, 6145, 5754, 6536),
       cholesterol = c(6309, 11104, 108, 7059, 12345, 10622),
              urea = c(1904, 1430, 1868, 1743, 1368, 1863)
)
file$date <- rep(1:3, 2)