Geom_path(linejoin = "mitre")

The code below does not mitre the path segments as in the geom_path() documentation.

Could you please tell me how I might get this to work?

Many thanks,



tibble(x = 0:2, y = c(0, 1, 0), size = c(8, 4, 4)) %>% 
  ggplot(aes(x, y, size = size)) +
  geom_path(linejoin = "mitre") +
  scale_size(range = c(4, 8)) +

1 Like

Hmm… Interesting, I'm seeing the same thing. For similicity's sake, I think the exact replication of the example using linejoin = "mitre" from the example is probably most useful to show. I'm also going to use reprex to show the problem (always a good way to go):

# Control line join parameters
df <- data.frame(x = 1:3, y = c(4, 1, 9))
base <- ggplot(df, aes(x, y))
base + geom_path(size = 10, linejoin = "mitre", lineend = "butt")

Created on 2018-01-13 by the reprex package (v0.1.1.9000).

And the example with the same code from the docs:
Example of linejoin mitre from ggplot2 docs

Bonus forensic investigation :mag_right:: I checked out the ggplot2 repo, and looked for issues mentioning mitre or linejoin. The most recent was 2014, however, the pull request that closed it wasn't long ago. Then I looked for the most recent mention of linejoin in (4 years ago), searched for "linejoin", found somewhat recent changes for linejoin in geom_segment.R, but, this was in geom_path(). However, that doesn't necessarily mean they're unrelated.

I could probably investigate further, but, I think it makes sense to open an issue.


This is my first post to the RStudio Community, and I'm very grateful for your prompt reply, your research, and your suggestions.

I've submitted a ggplot2 issue.

Many thanks!


1 Like

Perfect! Thanks for pointing it out— issues can be an excellent source of QA.