[ncl-talk] gsn_Spread_Colors issue

[Rashed Mahmood]

Hi all,

It seems that there is a possible issue (may be a previously known one)
when using "gsnSpreadColors" resource. There is difference of one color
between colorbar of a map plot and manual creation of colorbar with same
levels and colors.

The attached simple script "colorbar_test.ncl" creates dummy data and runs
"as is". The top two lines and the following two can be turned on and off
to create attached fig_1 and fig_2, each containing two colorbars one for
map (upper one) and one for coloured markers (lower one). For fig_1 the
colorbars are same (from 0 to onwards) however in fig_2 the central color
is different. The only difference for plotting these is the number of
levels (odd or even).

As a test, when I used same script using "cnFillPalette", in attached
script named "No_problem_script.ncl", the colorbars are exactly same for
both contour levels. The "no problem" figures are also attached.

I think this is related to how the colours are spanned in two routines
"gsnSpreadColors" and "cnFillPalette", but still it is surprising to see
the differences in colorbars of fig_1 and fig_2.


Any thoughts on this would be appreciated. I should now be using
"cnFillPallette", always!

Cheers,
Rashed
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