CODEWITHSUNDEEP
rggplot2plotlineadjustment
Vay
Vay

Reputation: 3

How can I adjust the linetype in an already existing ggplot model in R?

To examine an interaction effect in my research I've created post hoc slopes using the function “emtrends” of the package emmeans (version 1.4.5.; Lenth, 2020) and visualized it in a plot using 'emmip'. I've used the code below:

emtrends(model_c, pairwise ~ Condition, var = "prsa_clean$meat_amount_c")

emmip(model_c, Condition ~ meat_amount_c, cov.reduce = range, ylab = "Favourability", xlab = "Meat consumption")

The resulting plot shows the 3 slope lines of my 3 conditions in blue/green/red lines, but doesn't adhere to the APA standards for figures, so I'm trying to adjust it using ggplot2. I manage to successfully edit the background and linesizes to my liking using the code below:

plot <- emmip(model_c, Condition ~ meat_amount_c, cov.reduce = range, ylab = "Favourability", xlab = "Meat consumption")

plot <-plot +theme_bw() + geom_line(size = 1.25)

However, I would like the lines to be different types. I've found the appropriate code to adjust this with ggplot is to use the function geom_line(linetype = ""). I've tried to add the code in the same way as the theme and linesize, but it doesn't work. Example tries of code below:

plot <- plot +theme_bw() + geom_line(size = 1.25) + geom_line(linetype = "dashed")

plot <- plot +theme_bw() + geom_line(size = 1.25) + geom_line(aes(linetype = Condition))

plot <- plot +theme_bw() + geom_line(size = 1.25) + scale_linetype_manual(values=c("twodash", "dotted", "solid"))

I'm not a regular R user so I'm probably missing something pretty obvious. I hope someone can help me out.

In sum, I expected the geom_line(linetype="") argument to change the existing lines in the plot to become the designated types, but they remained unchanged. The theme_() and geom_line(size=) worked similarly so I expected similar results.

Upvotes: 0

Views: 420

Answers (1)

Andy Baxter
Andy Baxter

Reputation: 7626

Following my comment I tried some things with the emmip helpfile examples.

  • You can change line size within emmip with linearg = list(size = 1.25)
  • You can add scale_linetype_manual to the output

Example code:

library(emmeans)

noise.lm = lm(noise ~ size * type * side, data = auto.noise)

emmip(noise.lm, type ~ side * size, CIs = TRUE,
      linearg = list(size = 1.25)) +
  ggplot2::scale_linetype_manual(values=c("twodash", "dotted"))

Upvotes: 0

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