On Thu, Nov 27, 2014 at 9:54 AM, Todd <toddr...@gmail.com> wrote:
>
> On Nov 26, 2014 10:04 PM, "Nathaniel Smith" <n...@pobox.com> wrote:
>>
>> The main differences in requirements are:
>> - for the color cycle, you want isoluminant colors, to avoid the issue
>> where one line is glaring bright red and one is barely-visible-grey.
>> For general-purpose 2d colormaps, though, you almost always want the
>> luminance to vary to help distinguish colors from each other.
>
> If you used isoluminance colors for the lines, wouldn't that mean a plot
> printed in grayscale would have all lines be the same shade of gray?
Yes. But IME it's very difficult to use greyscale alone to distinguish
between multiple plot lines no matter what: you can't go much beyond 2
lines before you either end up with hard-to-see lines (b/c they don't
have enough contrast with the white background) or the lines become
nigh-indistinguishable ("which one is the slightly-darker grey?"). And
if you have substantial luminance variation to make the greyscale
work, then the color images end up looking really weird (the scarlet
versus faint-yellow problem, where you end up emphasizing one set of
data over another -- emphasis should be done on purpose! in
matplotlib's current color cycle the yellow and cyan tend to
disappear).
If you're worried about greyscale then IMHO you should use different
line styles (solid/dashed/dotted/...) and/or use solid black for
everything and label the lines directly.
Which isn't to say that there's never any value in picking line colors
from a colormap, it's just more complicated than it seems :-).
-n
--
Nathaniel J. Smith
Postdoctoral researcher - Informatics - University of Edinburgh
http://vorpus.org
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