[ncl-talk] how to plot this triangle grids

[Mary Haley]

Qi,

I wasn't displaying the last color in the color bars, so here's a new
version of the script.

In order to avoid white as a fill color, I added a function that subsets
the color map of interest, so you can indicate what part of the color map
to start and end at.

Finally, I got the script to run much faster (from 133 seconds to less than
a second) by creating a new version of "get_color_rgba" that allows
multiple data values to be input. I will make sure this updated function
gets into NCL V6.5.0. Meanwhile, I included it with this new script and
called it "get_color_rgba_improved")

--Mary

On Thu, Jul 27, 2017 at 6:27 PM, Mary Haley <haley at ucar.edu> wrote:

> Qi,
>
> I agree, this is an interesting plot.
>
> The key thing is that you need to do the following:
>
>
>    - Use gsn_csm_blank_plot to set up the X and Y axes for whatever
>    limits you need
>
>    This will be based on the number of boxes you need to have in the
>    matrix in both directions.
>
>    You could set up the axes limits to go from 0 to nxbox-1 in the X
>    direction, and 0 to nybox-1 in the Y direction, where "nxbox" will be, say,
>    the number of models you have, and "nybox" is the number of variables.
>
>    http://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_csm
>    _blank_plot.shtml
>
>    - For each variable and each model, you need to get the four values
>    for each triangle, and color each triangle based on the range it falls in.
>
>    You can use get_color_rgba to pass a color map, a set of numeric
>    levels, and a single value, and it will return an RGBA value that
>    represents the correct color for that value.
>
>    http://www.ncl.ucar.edu/Document/Functions/Built-in/get_colo
>    r_rgba.shtml
>
>    - You would then use either gsn_polygon or gsn_add_polygon to fill the
>    triangle in that color.  I recommend using gsn_add_polygon, so you can
>    actually attach it to the plot (in case the plot needs to be resized later
>    in a panel or some other reason).
>
>    http://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_add
>    _polygon.shtml
>
>    - Finally, to attach the extra labelbars, you can use
>    gsn_create_labelbar and gsn_add_annotation.
>
>
> I realized all of this sounded a bit daunting, so I created a script using
> dummy data, which I've attached.
>
> The scrip creates an nvars x nmodels x nlat x nlon dummy array, and then
> takes the min, max, average, and standard deviation for each nlat x nlon
> section and used these values to fill in the four triangles in each
> quadrant.
>
> This script is somewhat slow in the add_triangles code, and I think this
> is partly because of the loop that gets the color value for each data
> point.  I will see if I can speed this up.
>
> --Mary
>
>
> On Wed, Jul 26, 2017 at 10:18 AM, LI Qi <liqi123sh at qq.com> wrote:
>
>> Dear Mary,
>> Thanks for the quick reply.
>> My friend asked me the question and he would like to use the quadrants to
>> represent four seasons.
>> I'll forward the example to him.
>> It's really interesting, like expanding a dimension on the matrix.
>> Thanks again,
>> Best,
>> Qi
>>
>>
>> ------------------ Original ------------------
>> *From: * "Mary Haley";<haley at ucar.edu>;
>> *Date: * Wed, Jul 26, 2017 11:53 PM
>> *To: * "LI Qi"<liqi123sh at qq.com>;
>> *Cc: * "ncl-talk"<ncl-talk at ucar.edu>;
>> *Subject: * Re: [ncl-talk] how to plot this triangle grids
>>
>> Dear Qi,
>>
>> We have an example similar to this.  Please see:
>>
>> http://www.ncl.ucar.edu/Applications/table.shtml#ex6
>>
>> This uses dummy data, but hopefully you can modify this to create four
>> triangles per square.
>>
>> If you can provide the data, then I can help you come up with a script.
>>
>> --Mary
>>
>>
>> On Wed, Jul 26, 2017 at 9:29 AM, LI Qi <liqi123sh at qq.com> wrote:
>>
>>> Dear NCL,
>>>
>>> I'd like to ask how to plot the attached fig.
>>> It's RMSE, the four quadrants in one grid representing four different
>>> reanalysis.
>>> Is this plot attributed to triangle mesh or raster fill?
>>> Thanks for any light shed on this.
>>>
>>> Qi
>>>
>>>
>>> The “portrait” diagram of relative spatially averaged RMSEs in the
>>> 1981–2000 climatologies of temperature and precipitation indices simulated
>>> by the CMIP5 models with respect to the four reanalyses, ERA40 (left
>>> triangle), ERA-Interim (upper triangle), NCEP1 (right triangle), and NCEP2
>>> (lower triangle). The RMSEs are spatially averaged over global land grid
>>> points. The top row indicates the mean relative RMSE across all indices for
>>> a particular model and the grey-shaded columns on the right side indicates
>>> the standardized median RMSEmedian,std for CMIP3 and CMIP5 (see text
>>> for details).
>>>
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> ncl-talk at ucar.edu
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>
>>>
>>
>
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