[R] color scale mapped to B/W

[hadley wickham]

On Fri, Jun 6, 2008 at 6:23 PM, Achim Zeileis
<Achim.Zeileis at wu-wien.ac.at> wrote:
> On Fri, 6 Jun 2008, Michael Friendly wrote:
>
>> In an R graphic, I'm using
>>
>> cond.col <- c("green", "yellow", "red")
>> to represent a quantitative variable, where green means 'OK', yellow
>> represents 'warning'
>> and red represents 'danger'. Using these particular color names, in B/W,
>> red is darkest
>> and yellow is lightest.  I'd like to find color designations to replace
>> yellow and green so
>> that when printed in B/W, the yellowish color appears darker than the
>> greenish one.
>>
>> Is there some tool/code I can use to find these? i.e., something to
>> display a grid
>> of color swatches with color codes/names I can look at in color and B/W to
>> decide?
>
> You could look at colors in HCL (i.e., polar LUV). For example, you could
> choose a dark red HCL = (0, 90, 40) and a light green (120, 70, 90) and a
> yellow somewhere in between.

How did you get to those numbers?  I seem to remember there being
someway to convert rgb to hcl, but I can't find it.

Hadley


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