Is it possible to get a downward pointing solid triangle plotting symbol in R?

?s 10:09 de 06/10/2023, Chris Evans via R-help escreveu:

The reason I am asking is that I would like to mark areas on a plot using geom_polygon() and aes(fill = variable) to fill various polygons forming the background of a plot with different colours. Then I would like to overlay that with points representing direction of change: improved, no reliable change, deteriorated. The obvious symbols to use for those three directions are an upward arrow, a circle or square and a downward pointing arrow.? There is a solid upward point triangle symbol in R (ph = 17) and there are both upward and downward pointing open triangle symbols (pch 21 and 25) but to fill those with a solid colour so they will be visible over the background requires that I use a fill aesthetic and that gets me a mess with the legend as I will have used a different fill mapping to fill the polygons.? This silly reprex shows the issue I think.

library(tidyverse)
tibble(x = 2:9, y = 2:9, c = c(rep("A", 5), rep("B", 3))) -> tmpTibPoints
tibble(x = c(1, 5, 5, 1), y = c(1, 1, 5, 5), a = rep("a", 4)) -> tmpTibArea1
tibble(x = c(5, 10, 10, 5), y = c(1, 1, 5, 5), a = rep("b", 4)) -> tmpTibArea2
tibble(x = c(1, 5, 5, 1), y = c(5, 5, 10, 10), a = rep("c", 4)) -> tmpTibArea3
tibble(x = c(5, 10, 10, 5), y = c(5, 5, 10, 10), a = rep("d", 4)) -> tmpTibArea4
bind_rows(tmpTibArea1,
 ????????? tmpTibArea2,
 ????????? tmpTibArea3,
 ????????? tmpTibArea4) -> tmpTibAreas
ggplot(data = tmpTib,
 ?????? aes(x = x, y = y)) +
 ? geom_polygon(data = tmpTibAreas,
 ?????????????? aes(x = x, y = y, fill = a)) +
 ? geom_point(data = tmpTibPoints,
 ???????????? aes(x = x, y = y, fill = c),
 ???????????? pch = 24,
 ???????????? size = 6)

Does anyone know a way to create a solid downward pointing symbol?? Or another workaround?

TIA,

Chris

Hello,

Maybe you can solve the problem with unicode characters.
See the two scale_*_manual at the end of the plot.



# Unicode characters for black up- and down-pointing characters
pts_shapes <- c("\U25B2", "\U25BC") |> setNames(c("A", "B"))
pts_colors <- c("blue", "red") |> setNames(c("A", "B"))

ggplot(data = tmpTibAreas,
      aes(x = x, y = y)) +
 geom_polygon(data = tmpTibAreas,
              aes(x = x, y = y, fill = a)) +
 geom_point(data = tmpTibPoints,
            aes(x = x, y = y, color = c, shape = c),
            size = 6) +
 scale_shape_manual(values = pts_shapes) +
 scale_color_manual(values = pts_colors)