njtierney/ishihara

Create Ishihara plates in R

ishihara

The goal of ishihara is to create an Ishihara test, which can help assess colourblindness.

There are a few implementations of this test around the web, but I haven’t seen one that worked for R, so here is my crack at implementing it.

Note that this is a work in progress, don’t use it for proper testing.

Installation

The development version from GitHub with:

# install.packages("devtools")
devtools::install_github("njtierney/ishihara")

Proof of Concept

I had an idea on how I could maybe create this kind of figure in R, using spatial tools. The general process is:

1. Create a bunch of circles with packcircles
2. Convert that to an SF object
3. Pull in a vector font from gridfont
4. Convert that font into an SF object
5. Overlay the two SF objects and see where they intersect
6. Plot the circles that are intersected by the text
7. Change the colour palette in ggplot2 to see the impact of colourblindness

library(ishihara)
## basic example code
library(ggplot2)

I’m still working through the details of the implementation and usability, but the general idea is to create something like this:

set.seed(2020-05-10)
cb_1 <- ishihara_data("1")
gg_ishihara <- gg_ishihara(cb_1)
gg_ishihara
gg_ishihara + scale_fill_brewer(palette = "Dark2")
gg_ishihara + scale_fill_viridis_d()
gg_ishihara + scale_fill_manual(values = c("black", "grey90"))
gg_ishihara + scale_fill_manual(values = c("red", "green"))

ishihara's Issues

identify "correct" colourblind colours to use

add mottled colours to the two areas

it's not just green + red, but a few different shades of green and red

Center + scale a stimulus onto the plate

So that you can use many characters, or even images and stuff

Allow for multiple letters/symbols to be combined

read in vector fonts as shapefile

So that any font can be used and placed onto a plate

Get the circle size + padding right

It still doesn't quite look right, compared to the standard plates

add squiggly lines