ggplot - set a special width for one line

[rama27]

Hi, I have a following problem. I would like to make a ggplot and set width for one particular line.

See my example:

ggplot(final_data) +
  geom_line(aes( x = Season, y = competitionLevelNum, color= horseLicence ) )   

In other words - If and only if horseLicence = "KJ0G0V", make the width of the line 0.5.

But when I try this:

ggplot(final_data) +
  geom_line(aes( x = Season, y = competitionLevelNum, color= horseLicence ) ) +
  geom_line(aes( x = Season, y = competitionLevelNum, horseLicence = "KJ0G0V", lwd=0.5))

I got a nonsense with a warning message "Ignoring unknown aesthetics: horseLicence ".

Can someone help me, please? Thanks a lot!

[mfherman]

There are a number of ways to do this, depending on your data and use case. I particularly like gghighlight -- this vignette describes the many options it has. Here are a few examples:

library(tidyverse)

set.seed(1)

df <- tibble(
  time = rep(1:5, 3),
  class = rep(letters[1:3], 5),
  value = rnorm(15)
  )

# set size of lines manually
df %>% 
  ggplot(aes(time, value, color = class)) +
  geom_line(aes(size = class)) +
  scale_size_manual(values = c(a = 3, b = 0.5, c = 0.5))

# draw wider line separately from others and set size
df %>%
  filter(class != "a") %>% 
  ggplot(aes(time, value, color = class)) +
  geom_line() +
  geom_line(data = filter(df, class == "a"), size = 3)

# use gghighlight()
df %>% 
  ggplot(aes(time, value, color = class)) +
  geom_line() +
  gghighlight::gghighlight(class == "a")

^{Created on 2020-06-01 by the reprex package (v0.3.0)}