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

[Chris Evans]

Sadly, no.  Still shows the same legend with both sets of fill 
mappings.  I have found a workaround, sadly
much longer than yours (!) that does get me what I want but it is a real 
bodge.  Still interested to see
if there is a way to create a downward pointing solid symbol but here is 
my bodge using new_scale_fill()
and new_scale_color() from the ggnewscale package (many thanks to Elio 
Campitelli for that).

library(tidyverse)
library(ggnewscale) # allows me to change the scales used
tibble(x = 2:9, y = 2:9,
        ### I have used A:C to ensure the changes sort in the correct 
order to avoid the messes of using shape to scale an ordinal variable
        ### have to say that seems a case where it is perfectly sensible 
to map shapes to an ordinal variable, scale_shape_manual() makes
        ### this difficult hence this bodge
        c = c(rep("A", 5), "B", rep("C", 2)),
        change = c(rep("Deteriorated", 5), "No change", rep("Improved", 
2))) %>%
   ### this is just keeping the original coding but not used below
   mutate(change = ordered(change,
                           levels = c("Deteriorated", "No change", 
"Improved"))) -> tmpTibPoints
### create the area mapping
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
### now plot
ggplot(data = tmpTib,
        aes(x = x, y = y)) +
   geom_polygon(data = tmpTibAreas,
                aes(x = x, y = y, fill = a),
                alpha = .5) +
   scale_fill_manual(name = "Areas",
                     values = c("orange", "purple", "yellow", "brown"),
                     labels = letters[1:4]) +
   ### next two lines use ggnewscale functions to reset the scale mappings
   new_scale_fill() +
   new_scale_colour() +
   ### can now use the open triangles and fill aesthetic to map them
   geom_point(data = tmpTibPoints,
              aes(x = x, y = y, shape = c, fill = c, colour = c),
              size = 6) +
   ### use the ordered variable c to get mapping in desired order
   ### which, sadly, isn't the alphabetical order!
   scale_shape_manual(name = "Change",
                    values = c("A" = 24,
                               "B" = 23,
                               "C" = 25),
                    labels = c("Deteriorated",
                               "No change",
                               "Improved")) +
   scale_colour_manual(name = "Change",
                    values = c("A" = "red",
                               "B" = "grey",
                               "C" = "green"),
                    labels = c("Deteriorated",
                               "No change",
                               "Improved")) +
   scale_fill_manual(name = "Change",
                    values = c("A" = "red",
                               "B" = "grey",
                               "C" = "green"),
                    labels = c("Deteriorated",
                               "No change",
                               "Improved"))

That gives the attached plot which is really what I want.  Long bodge 
though!*
*

On 06/10/2023 11:50, Jan van der Laan wrote:
>
> Does adding
>
> , show.legend = c("color"=TRUE, "fill"=FALSE)
>
> to the geom_point do what you want?
>
> Best,
> Jan
>
> On 06-10-2023 11:09, Chris Evans via R-help wrote:
>> 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)
>
-- 
Chris Evans (he/him)
Visiting Professor, UDLA, Quito, Ecuador & Honorary Professor, 
University of Roehampton, London, UK.
Work web site: https://www.psyctc.org/psyctc/
CORE site: http://www.coresystemtrust.org.uk/
Personal site: https://www.psyctc.org/pelerinage2016/

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