mask the data relating to the contour of the continents

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Carlos Batista 2014-7-11

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回答： Chad Greene 2014-12-5

采纳的回答： Chad Greene

Does anyone have a solution to mask the data relating to the contour of the continents of a netcdf file?

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Carlos Batista 2014-7-11

I'm having a doubt that the following (...)

I am using netcdf data of sea surface temperature (SST) of the entire globe. I have these file data of SST and the values of the contours of the continents (32767 values).

I write this for this script

NCID netcdf.open = ('anom.sst.nc', 'NC_NOWRITE'); %%%%%%%% LONGITUDE [sst, xtype, varDimIDs, varAtts] = netcdf.inqVar (NCID, 0); varid = netcdf.inqVarID (NCID, sst); Lonn = double (netcdf.getVar (NCID, varid));

%%%%%%%% LATITUDE [sst, xtype, varDimIDs, varAtts] = netcdf.inqVar (NCID, 1); varid = netcdf.inqVarID (NCID, sst); LATN = double (netcdf.getVar (NCID, varid));

%%% time [sst, xtype, varDimIDs, varAtts] = netcdf.inqVar (NCID, 2);

%%% time [sst, xtype, varDimIDs, varAtts] = netcdf.inqVar (NCID, 3);

%%% time [sst, xtype, varDimIDs, varAtts] = netcdf.inqVar (NCID, 4);

varid = netcdf.inqVarID (NCID, sst); % Open my date data = double (netcdf.getVar (NCID, varid));

%%%%%%%%%%%%%%%%%%%% My question is: How to inform pro Matlab does not consider the values of the contours of the continents?

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Answer 1

Chad Greene 2014-7-11

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https://ww2.mathworks.cn/matlabcentral/answers/141353-mask-the-data-relating-to-the-contour-of-the-continents#answer_144680

Perhaps inpolygon will do it?

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Carlos Batista 2014-7-11

Thanks Chad for your answer!!

Chad, the inpolygon isn't only for graphics? I need inform in matrix of Matlab that the value 32767 not is considerable!!! How declare for the matlab matrix that an value don't is considerable ??

Thanks again!

Chad Greene 2014-7-11

在 MATLAB Online 中打开

Perhaps I misunderstood your question. Here is what I thought:

My assumption was that you have a grid of SST data, a corresponding grid of latitudes, a grid of longitudes, and 32767 points that define the outline of the continents. If this is true, inpolygon should tell you which grid points are inside the outline of the continents.

But I think I misunderstood. If you have a grid where all land values are given the value 32767, set them to NaN by

SST(SST==32767)=NaN;

Then you can plot sea surface temperatures easily with pcolor or pcolorm.

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