[gradsusr] Shaded plot only for values above a minmum

[Jennifer Adams]

From the doc page on 'controlling colors': 
When using version 2.0.0+ and 'gxout shade2' or 'gxout shade2b', if any of the color numbers is < 0, the contour is not drawn at all (i.e., it is effectively transparent). In version 2.1+, the 'set gxout' option 'shaded' is an alias for 'shade2'. 
So if you have 'set clevs 9 10 11 12 13 14 15', add 'set ccols -1 9 14 4 11 5 13 3'  (or use your colors of choice) and then no contours with values below 9 will be drawn. 

Alpha values for defined colors were introduced in version 2.1. So you could also define a color to be completely transparent (e.g. 'set rgb 20 1 1 1 0')  and that would give you the same result as described above, but there's no need to overcomplicate.
--Jennifer


On Feb 28, 2014, at 11:12 PM, Jeff Duda wrote:

> I think if you're using version 2.0.2+ you can use alpha values to make the color below the bottom level transparent instead of matching the background.  Just display the underlying field first.
> Jeff
> 
> 
> On Fri, Feb 28, 2014 at 8:55 PM, Thomas Robinson <ter at hawaii.edu> wrote:
> Thank you Jeff.  I actually have a plot of terrain, and I would like to plot 'var' on top of that with the terrain in the background.  So I really want to make a shaded plot overlaid on a shaded plot.  Just using a background value won't work for that.  It there any way to just eliminate the lower values?
> 
> 
> On Fri, Feb 28, 2014 at 1:13 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:
> use the ccols command to manually set the color levels.  If you have N contour values, you need N+1 colors, the first one in the list is the color corresponding to values below the lowest contour.  Set that to 0 (background), so that it will appear not to color values below your minimum contour value.  See the controlling colors section of the documentation index for more information.
> 
> Jeff Duda
> 
> 
> On Fri, Feb 28, 2014 at 4:58 PM, Thomas Robinson <ter at hawaii.edu> wrote:
> Aloha Grads Users, 
> 
> I am trying to make a shaded plot where values only show up if they are greater than 9.  So I do:
> 
> set clevs 9 10 11 12 13 14 15
> d val
> cbarn
> 
> That works great, but it fills in purple (default) for everything below 9 which is most of the plot.  Is there a way to turn off coloring in the areas below 9?  
> 
> Thanks, 
> Tom
> 
> -- 
> Tom Robinson
> President - Graduate Student Organization 
> Chair - Student Athletic Fee Committee 
> Graduate Student - Department of Meteorology
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> -- 
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> -- 
> Tom Robinson
> President - Graduate Student Organization 
> Chair - Student Athletic Fee Committee 
> Graduate Student - Department of Meteorology
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> -- 
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr

--
Jennifer M. Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
111 Research Hall, Mail Stop 2B3
George Mason University
4400 University Drive
Fairfax, VA 22030 





-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20140301/096a8eee/attachment.html