[R] getting 21 very different colours
b@row||ng@on @end|ng |rom |@nc@@ter@@c@uk
Tue Sep 11 17:36:31 CEST 2018
On Tue, Sep 11, 2018 at 11:43 AM, Duncan Murdoch <murdoch.duncan using gmail.com>
> On 11/09/2018 3:34 AM, Federico Calboli wrote:
> > Hi All,
> > I am plotting a scatterplot of 21 populations, and I am using
> rainbow(21)[pops.col] to generate 21 colours for the plot (which works).
> Maybe it is because I can really process few colours at a time, but the
> differences between the colours are not as strong as I’d like. I can
> specify start and end for rainbow(), but if anything that looks worse if I
> do not just stick to 0 and 1.
> > Is there a way of getting a set of 21 colours that maximises the
> differences between them?
> The LAB and LUV color spaces (in the colorspace package) attempt to map
> perceptual differences to equal distances. You could try using a grid
> of points in one of those spaces, but not all triples are valid.
> However, 21 colours is probably too many for your purpose. If you
> really want to distinguish 21 groups, you're likely going to have to use
> other characteristics as well, such as the symbol. You could plot 21
> different letters in 5 different colours and it might work, but it's not
> going to be easy for viewers.
The `alphabet` and `alphabet2` palettes from the `pals` package claim 26
The ‘alphabet’ palette has 26 distinguishable colors that have
logical names starting with the English alphabet letters A, B, ...
Z. This palette is based on the work by Green-Armytage (2010), but
uses the names 'orange' instead of 'orpiment', and 'magenta'
instead of 'mallow'.
There are some other palettes in that help page (?alphabet) that might also
work. But 21 colours is pushing it.
> Duncan Murdoch
> > I could pick them by hand, but that is about 15 colours more than I know
> (I have a detailed colourchart, but the visual differences between
> ’skyblue’ and ’slategrey’ elude me when plotted as dots on a plot).
> > Cheers
> > F
> > --
> > Federico Calboli
> > LBEG - Laboratory of Biodiversity and Evolutionary Genomics
> > Charles Deberiotstraat 32 box 2439
> > 3000 Leuven
> > +32 16 32 87 67
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