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I have been battling for a long time now to find a way to change the legend key of a ggplot2 with a hexagon. Any help or guidance are highly appreciated!

library(ggplot2)
set.seed(123)
ggplot(iris) +
  geom_jitter(aes(x=Species,y=Sepal.Length,color=Species),width=0.25) +
  guides(color= guide_legend(override.aes = list(shape = 21)))

Created on 2021-11-13 by the reprex package (v2.0.1)

tjebo
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LDT
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1 Answers1

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You can create keys using grid commands and then pass to a geom_ using the key_glyph argument.

A quick example:

library(grid)
library(ggplot2)

draw_key_hex <- function (data, params, size) {
    # hexagon vertex coordinates 
    v <- list(x = c(0.95, 0.725, 0.275, 0.05, 0.275, 0.725), 
              y = c(0.5, 0.110288568297003, 0.110288568297003, 0.5, 0.889711431702997, 0.889711431702997))
    # hexagon grob
    polygonGrob(v$x, v$y, 
                gp = gpar(col = data$colour,
                          fill = alpha(data$fill, data$alpha)))
}

set.seed(123)
ggplot(iris, aes(x=Species,y=Sepal.Length,color=Species)) +
  geom_jitter(width=0.25, key_glyph=draw_key_hex) 


# or with fill
set.seed(123)
ggplot(iris, aes(x=Species,y=Sepal.Length,color=Species, fill=Species)) +
  geom_jitter(width=0.25, key_glyph=draw_key_hex)

tjebo
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user20650
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    Great answer. You should add a picture of the output. It might be worth pointing out that if the hexagons look a bit small you can still increase their size by adding the line `guides(color= guide_legend(override.aes = list( size = 20)))` – Allan Cameron Nov 13 '21 at 23:06