geom_path(linejoin = "mitre")

[behrman]

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

Bill

suppressMessages(library(tidyverse))

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)) +
  coord_fixed()

[batpigandme]

Thanks, Bill. Just adding my snippets from the community thread since I have them, so it'll (hopefully) be easier to navigate sources when we troubleshoot.

Exact replication of the example using linejoin = "mitre" from the doc example

# Control line join parameters
library(ggplot2)
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:

Bonus forensic investigation 🔎: 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 NEWS.md (4 years ago), searched for "linejoin", found somewhat recent changes for linejoin in geom_segment.R, but, this was in geom_path().

[Ax3man]

The documented example works as expected for me on 2.2.1. Using differently sized segments (as in OPs example) never works, as the segments get connected by size and therefore respond to the lineend parameter, not the linejoin.

[batpigandme]

Interesting, the CRAN version (2.2.1) works as expected (see reprex below), but the dev version does not (shown in #2399 (comment), above, tidyverse/ggplot2@3fb3fb0)

# Control line join parameters
library(ggplot2)
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")

[Ax3man]

Possibly related to 3553f31?

[batpigandme]

@Ax3man good call. 👍 Works as it should when linemitre = 1 is passed as an argument. @behrman, your example doesn't work, but, as mentioned, I think that has to do with the change in size at the line joins.

library(ggplot2)
df <- data.frame(x = 1:3, y = c(4, 1, 9))
base <- ggplot(df, aes(x, y))
base + geom_path(size = 10, linejoin = "mitre", linemitre = 1)

Created on 2018-01-15 by the reprex package (v0.1.1.9000).

n.b. When passed linemitre = 10, it appears un-mitred. (@hadley, not sure if this is what's meant by better matching base R, per the comment in 3553f31).

library(ggplot2)
df <- data.frame(x = 1:3, y = c(4, 1, 9))
base <- ggplot(df, aes(x, y))
base + geom_path(size = 10, linejoin = "mitre", linemitre = 10)

Created on 2018-01-15 by the reprex package (v0.1.1.9000).

[behrman]

Yes, mitering works when the line segments are the same size, but doesn't work when the segments are of different sizes. Is there any way to get this to work for segments of different sizes?

I'm using ggplot2 2.2.1.9000.

Thanks

[hadley]

I don't think so - the underlying grid grob doesn't support varying widths.

[batpigandme]

Since it sounds like this isn't possible, I'm gonna go ahead and close the issue.

[lock]

This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/