[ncl-talk] transparency in xy line plot

[Rick Brownrigg]

Hi Julie,


How are you setting the color(s) of the 30 ensemble members?  If they are
being set to one color via xyLineColor, and set with a 3-tuple, you can of
course make that a 4-tuple with the 4th component being translucency.  If
they are set via an array of 3-tuple colors and xyLineColors, the you can
do something like:

   dims = dimsizes(myColors)
   myColorsWithAlpha = new((/ dims(0), dims(1)+1/), float)
   myColorsWithAlpha(:, 0:2) = myColors
   myColorsWithAlpha(:, 3) = 0.25   ; sets all colors alpha/tranlucency to
.25

If they are set via one or more named colors, there's the function
"namedcolor2rgba"
that would give you an array of 4-tuples, from which you can set the alpha
channel accordingly.

If none-of-the-above, please send me the relevant code fragments and I'll
see if I can't help.

FWIW...the lack of a xyLineOpacityF resource seems like an omission, and
may indeed be a bug ticket (if not, it will be!).

Rick


On Mon, May 2, 2016 at 7:21 PM, Julie Arblaster <julie.arblaster at monash.edu>
wrote:

> Hello,
>
> I am using gsn_csm_xy to plot 30 timeseries from 30 ensemble members on
> one XY plot. I would like to make these slightly transparent using the new
> color model so that when I overlay the ensemble mean it stands out but is
> in the same colour. But I can't find a xyLineOpacityF resource. Can I
> achieve this somehow with other resources easily?
>
> Thanks,
> Julie
>
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