[ncl-talk] color index exceeds size of palette

[Rick Brownrigg]

(sorry -- hit send before completing the note :-/  )

Looking at the color palette you are using:

http://ncl.ucar.edu/Document/Graphics/ColorTables/BlueDarkRed18.shtml

We see the indices going from 2 to 19, which seems a bit confusing.
However, once adjusted by -2, the range of valid values would of course be
0 to 17, and thus that value of 18 in your cnFillColors setting
should/would elicit the error message being reported.

I hope that makes sense(?)

Rick


On Sat, May 12, 2018 at 10:41 AM, Rick Brownrigg <brownrig at ucar.edu> wrote:

> Hi,
>
> Historically, the first two colors in a colormap were reserved as
> "background" and "foreground" colors, typically black and white. To
> preserve backwards compatibility, that is still the case when colors are
> associated with the *workstation*. However, in the case of colormaps that
> are loaded into a *palette* that is expressly used for contouring, vectors,
> streamlines, etc. those first two colors are stripped out of the colormap.
> So I think the short answer is you want to adjust all your color indices by
> -2 (except of course the -1 indexes designating "TRANSPARENT".
>
> Looking at the color palette you are using:
>
> http://ncl.ucar.edu/Document/Graphics/ColorTables/BlueDarkRed18.shtml
>
> We see the indices going from 2 to 19
>
> On Sat, May 12, 2018 at 7:58 AM, Anne <anne.seidenglanz at unive.it> wrote:
>
>> Hi all,
>>
>> I want to plot some anomaly; for these difference plots I have
>> used cnLevelSelectionMode = "ExplicitLevels" in order to specify both my
>> contour levels as well as specific colors after that. I have used the
>> pre-defined "BlueDarkRed18" color table; my specified cnFillColors are well
>> within the range of this colour table (3 to 18; see script attached),
>> nevertheless I receive the error message
>>
>> "color index exceeds size of palette, defaulting to foreground color of
>> entry"
>>
>> Why is this? Sorry if I have missed something from the documentation.
>> I have attached both the script and an example plot (last plot).
>>
>> Any help is appreciated,
>> thanks
>> Anne
>>
>> Nota automatica aggiunta dal sistema di posta.
>>
>> _______________________________________________
>> ncl-talk mailing list
>> ncl-talk at ucar.edu
>> List instructions, subscriber options, unsubscribe:
>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20180512/cc7bf49d/attachment.html>