change segment grob to curve

[malcolmbarrett]

I was recently inspired by the annotation in the BBC R cookbook, which uses a curved line. It occured to me that this would be relatively easy to implement in ggrepel by changing segmentsGrob() to curveGrob() with the curvature set to 0 by default. This PR implements that change, adding the arguments segment.curvature, segment.angle, and segment.ncp to both repel geoms.

The default behavior remains the same.

library(ggrepel)
library(dplyr)

set.seed(3233)

p <- mtcars %>% 
  dplyr::mutate(lbls = rownames(mtcars)) %>% 
  ggplot(aes(wt, mpg, label = lbls, colour = factor(cyl))) +
  geom_point()

p + geom_text_repel()

But now you can add a curve (and control the details, as in geom_curve())

p + geom_text_repel(
  data = function(x) dplyr::sample_n(x, 3),
  nudge_y = 2,
  nudge_x = 1,
  segment.curvature = -.3,
  segment.angle = 80,
  segment.ncp = 3
)

p + geom_label_repel(
  data = function(x) dplyr::sample_n(x, 3),
  nudge_y = 2,
  nudge_x = 1, 
  segment.curvature = .5, 
  segment.ncp = 6,
)

Plus, you can do some fun annotation stuff with it.

p + geom_text_repel(
  data = function(x) dplyr::sample_n(x, 3),
  nudge_y = 1,
  nudge_x = 1,
  point.padding = .3,
  segment.curvature = -1e-20,
  segment.angle = 10,
  arrow = arrow(length = unit(0.02, "npc"), type = "closed")
)

^{Created on 2019-03-05 by the reprex package (v0.2.1)}

[slowkow]

This looks awesome!

Thank you so much for the contribution. I look forward to merging.

Would you consider making a new example for the vignette that highlights this new feature?

[malcolmbarrett]

Yes, happy to! I'll try to add one tomorrow

[malcolmbarrett]

I updated the news and added an example. I didn't rebuild the vignette because I had some trouble with the makefile 😇

[malcolmbarrett]

That Travis error on R-devel doesn't seem to have to do with the commit. The others built fine, and I rebuilt it on my copy of the repo, and all three worked 🤷‍♂️

[slowkow]

My best guess is that the failure is due to a network issue on the Travis CI servers.

I see:

* checking for future file timestamps ...Warning in file(con, "r") :
  cannot open URL 'http://worldclockapi.com/api/json/utc/now': HTTP status was '403 Forbidden'
 WARNING
unable to verify current time

To me, that means that Travis tried to get the current time from a 3rd party and failed.

I didn't know that checking a package would look for future time stamps! Pretty cool, I guess, if you trust data served by worldclockapi.com.

[malcolmbarrett]

ha, I've had Travis time out on me before, but that's a new one! Anyway, let me know if you need me to do anything else before merging 👍