Is there a layer using ggplot2 in R to customise the x-axis?

Question

I'm trying to create an x-axis that decreases then increases. It's for a lab where we cooled down shrimp and counted the pleopod beats every 2C change.

Here's one set of the data:

Temperature	Starved Individual 1
20	57
18	53
16	54
14	50
12	49
10	43
8	41
6	42
4	39
6	41
8	45
10	49
12	57
14	60
16	57
18	58
20	71

This is the code I've used and the plot it creates, but I can't figure out how to make the x-axis go from 20-4-20.

 s1 <- ggplot(wide_artemia_data, aes(temperature, beats_s1)) + 
  xlab("Temperature (C)") + 
  ylab("Number of Pleopod Beats over 30 sec")

s1 + geom_point()

This is my first time trying to learn to code and use R studio, so any help or tips would be greatly appreciated!

Answer 1

Your x-axis needs to be unique, but you can add one, and show something else:

wide_artemia_data <- read.table(text=
"Temperature    Starved Individual 1
20  57
18  53
16  54
14  50
12  49
10  43
8   41
6   42
4   39
6   41
8   45
10  49
12  57
14  60
16  57
18  58
20  71
", header=TRUE, check.names=FALSE, sep="\t" )

wide_artemia_data$id <- 1:nrow( wide_artemia_data )
s1 <- ggplot(wide_artemia_data, aes(id, `Starved Individual 1`)) +
    scale_x_continuous( labels=wide_artemia_data$Temperature, breaks=wide_artemia_data$id ) +
    xlab("Temperature (C)") +
    ylab("Number of Pleopod Beats over 30 sec")
s1 + geom_point()

Result: