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I have created a graph to demonstrate the development of four variables. Is there any way to add a label that tells the percentage change(last observation/first observation -1) to the end of the plots to highlight the relative change during the observed period?

Data&plots=

library(tidyverse)

Data <- data.frame(
  Wind = c(236,325,470,615,647,821),
  Hard_coal= c(591,811,667,681,532,344),
  Gas= c(883,841,472,731,678,680),
  Bio = c(883,841,811,731,678,680),
  year= c("2015","2016","2017","2018","2019","2020"))

Data %>% 
  pivot_longer(-year) %>% 
  ggplot(aes(x = year, y = value, color = name, group = name, linetype = name)) +
  geom_line(size = 1.5)
Jrayman
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    (of course you need to calculate your percentage change first, but I trust you're able to do that) – tjebo Dec 12 '21 at 17:17
  • I also would be interested in how to calculate the percentage change and apply within this special case. Therefore I vote to reopen this question. Although the labeling issue is definitely covered by the answer link provided. The combination of calculation and labelling is not. – TarJae Dec 12 '21 at 18:36

1 Answers1

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Using the ggrepel option offered in Plot labels at ends of lines this could be achieved like so where I make use of dplyrs first and last to compute the percentage change.

Note: I still vote to close this question as a duplicate.

library(tidyr)
library(dplyr)
library(ggplot2)

data_long <- Data %>% 
  pivot_longer(-year) %>%
  mutate(year = as.numeric(year)) %>% 
  group_by(name) %>% 
  mutate(change = last(value) / first(value) - 1)

ggplot(data_long, aes(x = year, y = value, color = name, group = name)) +
  geom_line(size = 1) +
  ggrepel::geom_text_repel(data = filter(data_long, year == max(year)), 
                           aes(label = scales::percent(change)), 
                           direction = "y", nudge_x = .25,
                           hjust = 0, show.legend = FALSE) +
  scale_x_continuous(limits = c(NA, 2020.5)) +
  coord_cartesian(clip = "off")

stefan
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