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I am trying to draw a line with R's ggplot that starts on one facet and ends on another.

I believe this question was not asked yet (at least I could not find it) but I have found some example code that achieves exactly this: http://rstudio-pubs-static.s3.amazonaws.com/410976_f8eb6b218bfa42038a8b7bc9a6f9a193.html

However, documentation is weak and I did not manage to untangle the code. Can someone please provide an easily understandable version that illustrates the trick?

Here's some code as an example:

library(ggplot2)

df <- data.frame(x = 1:6, y = 1:6, facet = c(rep('A', times = 3), rep('B', times = 3)))

gg <- ggplot(data = df, mapping = aes(x = x, y = y)) + facet_grid(~ facet) +
  geom_line()
gg

line <- data.frame(x = 3, y = 3, 
                   xend = 4, yend = 4,
                   facet = 'A')

gg_line <- gg + geom_segment(data = line, mapping = aes(x = x, y = y,
                                                        xend = xend, yend = yend),
                             inherit.aes = FALSE, color = 'red')
gg_line

Obviously, in gg_line, the red geom_segment reaches the respective coordinates in facet A. However, I would like the end points to refer to the coordinates in facet B.

Any nudges to a working solution are highly appreciated!

okost
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  • [ggplot, drawing line between points across facets](https://stackoverflow.com/questions/31690007/ggplot-drawing-line-between-points-across-facets); [ggplot, drawing multiple lines across facets](https://stackoverflow.com/questions/42151880/ggplot-drawing-multiple-lines-across-facets?noredirect=1&lq=1), and Linked therein. – Henrik Jul 06 '21 at 09:48
  • Thanks, somehow I missed those – okost Jul 06 '21 at 09:51
  • Does this answer your question? [ggplot, drawing line between points across facets](https://stackoverflow.com/questions/31690007/ggplot-drawing-line-between-points-across-facets) – chemdork123 Jul 06 '21 at 18:53

0 Answers0