[gradsusr] How to save netcdf data without the outlines of the continents?

Sat Jul 12 18:14:58 EDT 2014

Carlos,

  In Matlab, just compress the 2D array into a 1D array, perform the
wavelet analysis on the 1D array, and map the results back into 2D arrays.
For example,

   I = isnan(sst)==false

   sst1 = sst(I) # remove undefs

  %% do calc with sst1, save result is 1D array r1, then

   r = NaN*zeros(size(sst))
   r(I) = r1 # this is a 2D array with NaN for undefs

   In retrospect, this is a matlab question, not a grads question.

      Arlindo

On Sat, Jul 12, 2014 at 8:45 AM, Carlos Batista <krlosbatist at gmail.com>
wrote:

> Olá Arlindo (...)
>
> Arlindo, meu problema é o seguinte (...)
>
> Estou tentando fazer umas análises de wavelets no Matlab usando dados
> netcdf de TSM. O problema é que o Matlab entende todas as informações como
> matrizes, inclusive os valores de undef e os que representam os contornos
> dos continentes.
> Esses valores de contornos dos continentes, por distoarem muito e por
> interferir nos calculos de wavelets, não podem estar na minha série de
> dados. Então, pensei se eu conseguisse tirar os dados referentes aos
> contornos dos continentes no GrADS e depois exportar apenas os dados das
> TSM poderia funcionar a matemática das wavelets
>
> Ontem eu consegui nomear todos esses valores de contornos com NaN com uma
> manobra dentro do próprio Matlab. Porém, mesmo esses NaN ainda estão
> atrapalhando no momento de fazer os calculos das wavelets (...) Fiz um
> teste pegando pontos de latitudes e longitudes com apenas os dados de TSM e
> o Matlab fez bem os calculos das wavelets.
>
> Penso que entrando apenas com os dados de TSM o matlab possa fazer as
> minhas wavelets!
>
> ****************************************************
> For Andrew
>
> I'm trying to do some analysis of wavelets in Matlab using netcdf SST
> data. The problem is that Matlab understands all information as matrix,
> including the values  undef and the representing the contours of the
> continents.
> These values of contours of continents for changer and interfere in my
> calculations of wavelets...  Like this these can not be in my dataset.
>
> So I thought if I could get the data to the contours of the continents in
> GrADS and then export only data from TSM could work the mathematics of
> wavelets
>
> Yesterday I managed to name all these contours with NaN values with a
> maneuver within Matlab itself. But even these are still messing NaN when
> you do the calculations of wavelets (...) I did a test taking points of
> latitude and longitude with only the SST data and Matlab did well the
> calculations of wavelets.
>
> I think just coming with SST matlab can make my wavelets!
>
> Thanks!!!
>
> Carlos
>
>
>
>
> 2014-07-12 2:09 GMT-03:00 Andrew Friedman <andfried at berkeley.edu>:
>
> I’ve also found that ‘sdfwrite’ is useful for exporting to Matlab, since
>> Matlab can open netcdf files.
>>
>> On Jul 11, 2014, at 8:14 PM, Arlindo da Silva <dasilva at alum.mit.edu>
>> wrote:
>>
>> > On Fri, Jul 11, 2014 at 1:11 PM, Carlos Batista <krlosbatist at gmail.com>
>> wrote:
>> >
>> > Dear Users
>> >
>> > I need to save the data  SST file without contours of continents.
>> >
>> > I need to open this data in Matlab. The Matlab understands the contours
>> as values and I don't know 'say' for the Matlab that data of contours is
>> not for "him" to read.
>> >
>> > Does anyone know?
>> >
>> >
>> > I really do not understand what you are trying to do. Which?
>> >
>> > 1) You are trying to import in matlab an image that you created in
>> grads, or
>> >
>> > 2)  You would like to open a binary SST file (that grads can read) in
>> matlab for further analysis,
>> >
>> >    Here is a very simple example of how to export ASCII data and import
>> it into Matlab,
>> >
>> >
>> http://cookbooks.opengrads.org/index.php?title=Recipe-002:_Saving_GrADS_variable_data_to_a_text_file
>> >
>> >    Here is a more sophisticated way of sharing data between grads and
>> matlab using Java:
>> >
>> >
>> http://opengrads.org/wiki/index.php?title=JyGrADS:_Java_and_Matlab_interface_to_GrADS_through_Jython
>> >
>> >    I never really released jygrads, but a working release can be found
>> here:
>> >
>> >          http://opengrads.org/devel/jygrads/
>> >
>> >    I hope this helps.
>> >
>> >         Arlindo
>> >
>> > --
>> > Arlindo da Silva
>> > dasilva at alum.mit.edu
>> > _______________________________________________
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>> > gradsusr at gradsusr.org
>> > http://gradsusr.org/mailman/listinfo/gradsusr
>>
>>
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-- 
Arlindo da Silva
*dasilva at alum.mit.edu <dasilva at alum.mit.edu>*
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