[ncl-talk] Adding text data in a contour plot

Kyle Griffin ksgriffin2 at wisc.edu
Wed Dec 2 14:07:31 MST 2015 

That looks like a great solution, Stefano. I'm cc'ing the NCL list here so
that others can see your solution in the future. Glad you were able to get
to a solution that plots faster!


Kyle

----------------------------------------
Kyle S. Griffin
Department of Atmospheric and Oceanic Sciences
University of Wisconsin - Madison
Room 1407
1225 W Dayton St, Madison, WI 53706
Email: ksgriffin2 at wisc.edu

On Wed, Dec 2, 2015 at 3:04 PM, Stefano Guerra <guerras90 at gmail.com> wrote:

> Hi, I'm using 6.3.0 version
>
> I solve the problem of slow process changing code in this way (latdef,
> londef and dataext are 2-d array):
>
>  contour_tc = wrf_contour(a,wks,tf2,opts)
>       plot = wrf_map_overlays(a,wks,(/contour_tc/),platres,mpres)
>       latout = fspan(36,47,46)
>       lonout = fspan(6.5,19,52)
>
>       do textlat = 0,45,1
>          do textlon = 0,51,1
>           loc  = wrf_user_latlon_to_ij(a, latout(textlat), lonout(textlon))
>         latdef(textlat,textlon) = latout(textlat)
>         londef(textlat,textlon) = lonout(textlon)
>         datatext(textlat,textlon) = tc2(loc(0),loc(1))
>         end do
>           end do
>
> text = gsn_add_text(wks,plot,sprintf("%0.0f",
> datatext),londef,latdef,txres)
> draw(plot)
>
> Without repeat "gsn_add_xx" function in the loops, but using arrays, i can
> add a lot of text point in the plot, i tried with a 150*120 2d array and
> works fine.
>
> Thank you very much,
> Stefano
>
> 2015-12-02 17:22 GMT+01:00 Kyle Griffin <ksgriffin2 at wisc.edu>:
>
>> What version of NCL are you using? I know some of the gsn_add_xxx
>> functions were made more efficient in recent NCL versions, but then again,
>> I don't see any official mention of those improvements including
>> gsn_add_text.
>>
>> Loops are notoriously inefficient in NCL. Could you try calling
>> gsn_add_text without the loop? Since you're using WRF, you may already have
>> 2d lat and lon variables, but since your code doesn't have them here, you
>> may want to create them (likely with the "conform" function and the
>> wrf_user_latlon... functions).
>>
>> If you are able to do that, you should then have 3 two-dimensional
>> variables: tc2, lat2d, and lon2d, containing the text to plot, the latitude
>> coordinate, and the longitude coordinate for every single point in the lat
>> x lon grid. At this point, you should be able to give each of these
>> variables to a single call of gsn_add_text and plot all the text at once,
>> rather than in 24*24 = 579 calls to the function.
>>
>> There may be a simple method to do this with the WRF functions (such as
>> retrieving 'lat' or 'lon' from the grid rather than creating it yourself)
>> that I'm not as familiar with, so explore some if you can!
>>
>>
>> Kyle
>>
>> ----------------------------------------
>> Kyle S. Griffin
>> Department of Atmospheric and Oceanic Sciences
>> University of Wisconsin - Madison
>> Room 1407
>> 1225 W Dayton St, Madison, WI 53706
>> Email: ksgriffin2 at wisc.edu
>>
>> On Wed, Dec 2, 2015 at 5:37 AM, Stefano Guerra <guerras90 at gmail.com>
>> wrote:
>>
>>> Hi Kyle, thank you for your answer.
>>>
>>> I tried this code, it works fine for my purpose, but there is a problem
>>> with time of execution. The first 7/8 "textlat" loops are sufficiently
>>> fast, but the following loops become very slow, than process fault.
>>>
>>> contour_tc = wrf_contour(a,wks,tf2,opts)
>>>       plot = wrf_map_overlays(a,wks,(/contour_tc/),platres,mpres)
>>> ;overlay per info confini
>>>       poly = gsn_add_shapefile_polylines(wks,plot,"reg2011_g.shp",pres)
>>> ;aggiungo shapefile confini regionali
>>>       latout = fspan(36,47,23)
>>>       lonout = fspan(7,18,23)
>>>       do textlat = 0,23,1
>>> print (textlat)
>>>          do textlon = 0,23,1
>>>          loc  = wrf_user_latlon_to_ij(a, latout(textlat),
>>> lonout(textlon))
>>>         text = gsn_add_text(wks,plot,sprintf("%0.0f",
>>> tc2(loc(0),loc(1))),lonout(textlon),latout(textlat),txres)
>>>         end do
>>>           end do
>>>
>>> draw(plot)
>>> frame(wks)
>>>
>>> Thank you again,
>>> Stefano.
>>>
>>> 2015-12-01 14:51 GMT+01:00 Kyle Griffin <ksgriffin2 at wisc.edu>:
>>>
>>>> Stefano,
>>>>
>>>> It'll take some additional lines of code, but gsn_add_text has the
>>>> functionality you are most likely looking for.
>>>>
>>>> https://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_add_text.shtml
>>>>
>>>> The biggest concern is that your x and y need to be individual pairs
>>>> corresponding to each and every grid point that you want the text at. In
>>>> essence, you would need a two-dimensional latitude array and
>>>> two-dimensional longitude array of only the points where you want text to
>>>> be plotted, as well as the values/strings you want plotted at those points.
>>>>
>>>> I would recommend trying this function with a small number of grid
>>>> points first to make sure it works and does what you want before trying to
>>>> make the function apply to an entire grid. This may prove to be a bit
>>>> trickier with a WRF grid, I have not worked with them myself so I'm not
>>>> sure. Let the list know if you have any problems/questions...
>>>>
>>>>
>>>> Kyle
>>>>
>>>> ----------------------------------------
>>>> Kyle S. Griffin
>>>> Department of Atmospheric and Oceanic Sciences
>>>> University of Wisconsin - Madison
>>>> Room 1407
>>>> 1225 W Dayton St, Madison, WI 53706
>>>> Email: ksgriffin2 at wisc.edu
>>>>
>>>> On Tue, Dec 1, 2015 at 5:31 AM, Stefano Guerra <guerras90 at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> I tried to search this function, but I couldn't find how can I add text
>>>>> data (from a WRF output) on a contour plot.
>>>>>
>>>>> Maybe I can explain better with an example, I want realize something
>>>>> like this:
>>>>>
>>>>> http://modeles2.meteociel.fr/modeles_gfs/runs/2015120106/3-580.GIF?01-6
>>>>>
>>>>>
>>>>> Thank you for your help,
>>>>> Stefano.
>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>
>>>
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>>
>
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