How to label lines obtained using split with ggrepel - r

Question

I am trying to label 4 lines grouped by the value of variable cc. To label the lines I use ggrepel but I get all the 4 labels instead of 2 for each graph. How to correct this error?
The location of the labels is in this example at the last date but I want something more flexible: I want to locate each of the 4 labels in specific points that I chose (e.g. b at date 1, a at date 2, etc.). How to do that?
library(tidyverse)
library(ggrepel)
library(cowplot)
set.seed(1234)
df <- tibble(date = c(rep(1,4), rep(2,4), rep(3,4), rep(4,4)),
country = rep(c('a','b','c','d'),4),
value = runif(16),
cc = rep(c(1,1,2,2),4))
df$cc <- as.factor(df$cc)
# make list of plots
ggList <- lapply(split(df, df$cc), function(i) {
ggplot(i, aes(x = date, y = value, color = country)) +
geom_line(lwd = 1.1) +
geom_text_repel(data = subset(df, date == 4),
aes(label = country)) +
theme(legend.position = "none")
})
# plot as grid in 1 columns
cowplot::plot_grid(plotlist = ggList, ncol = 1,
align = 'v', labels = levels(df$cc))
Created on 2021-08-18 by the reprex package (v2.0.0)

Answer 1

Here I make a tibble to hold color and position preferences, and join that to df.
The geom_text_repel line should probably use i instead of df so that it's split the same way as the line. The only trouble is this forces us to specify that we want four colors up front, since otherwise each chart would just use the two it needs.
set.seed(1234)
df <- tibble(date = c(rep(1,4), rep(2,4), rep(3,4), rep(4,4)),
country = rep(c('a','b','c','d'),4),
value = runif(16),
cc = rep(c(1,1,2,2),4))
label_pos <- tibble(country = letters[1:4],
label_pos = c(2, 1, 3, 2),
color = RColorBrewer::brewer.pal(4, "Set2")[1:4])
df <- df %>% left_join(label_pos)
df$cc <- as.factor(df$cc)
# make list of plots
ggList <- lapply(split(df, df$cc), function(i) {
ggplot(i, aes(x = date, y = value, color = color)) +
geom_line(lwd = 1.1) +
geom_text_repel(data = subset(i, date == label_pos),
aes(label = country), box.padding = unit(0.02, "npc"), direction = "y") +
scale_color_identity() +
theme(legend.position = "none")
})
# plot as grid in 1 columns
cowplot::plot_grid(plotlist = ggList, ncol = 1,
align = 'v', labels = levels(df$cc))