ggplotly not rendering unicode characters in `scale_shape` correctly

[rocanja]

When using unicode characters as shapes eg. scale_shape_manual(values=c("\u25BC","\u25FC","\u25B2")) they are rendered correctly with ggplot() but not with ggplotly(). Is ggplotly() not compatible with unicode or is there another workaround?

[trekonom]

Added a minimal reproducible example of the issue, which however also shows that using unicode symbols may also fail in ggplot2 and AFAIK depends on the font family:

library(ggplot2)
library(plotly, warn=FALSE)

ggplot(mtcars, aes(hp, mpg, shape = factor(cyl))) +
  geom_point(size = 4) +
  scale_shape_manual(values=c("\u25BC","\u25FC","\u25B2"))

ggplotly()

^{Created on 2023-02-15 with reprex v2.0.2}

[trekonom]

Just a guess, but the most likely reason for why ggplotly() fails to render the UTF-8 symbols is that the choice of marker symbols supported by plotly is large but limited. See the reference or Interactive web-based data visualization with R, plotly, and shiny for a list of available symbols.

[rocanja]

Thanks for pointing out these helpful resources @trekonom ! BTW, I could totally live with the basic R point shapes if there only was a 'filled triangle point-DOWN', the counterpart to pch=17 ... don't know how the R developers could miss this super important one ;) ... and yes, I am aware of pch=6 and pch=25, but having a 'filled triangle point-DOWN' would make things so much easier!

[rocanja]

Following the reference given by @trekonom to the page with the plotly supported symbols, here is the very straightforward solution for a 'filled triangle point-DOWN' for anyone coming across this issue:
scale_shape_manual(values=c("\U25BC","\U25CF","\U25B2")) for ggplot plots
scale_shape_manual(values=c("triangle-down","circle","triangle-up")) for plotly plots