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Define chunking behavior for NetCDF variable




netcdf.defVarChunking(ncid,varid,storage,chunkDims). sets the chunk settings for the variable specified by varid. Chunking is a technique to improve performance. storage specifies the type of chunking to use and chunkDims specifies the extents of the chunk size. You must specify the chunk size used with a variable after creating the variable but before you write data to the variable.

You cannot specify the chunk size for variables in a NetCDF file created with the netCDF-3 mode (CLASSIC_MODEL).

Input Arguments


Identifier of NetCDF file, returned by netcdf.create or, or of a NetCDF group, returned by netcdf.defGrp.


Identifier of a NetCDF variable, returned by netcdf.defVar.


Character vector specifying whether NetCDF should break the variable into chunks when writing to a file. If set to 'CHUNKED', NetCDF breaks the variable into chunks; if set to 'CONTIGUOUS', NetCDF does not break the data into chunks.


Array specifying the dimensions of the chunk.

Because MATLAB® uses FORTRAN-style ordering, the order of dimensions in chunkdims is reversed relative to what would be in the C API.

If storage is CONTIGUOUS, you can omit chunkDims.

Default: Chunk size determined by the NetCDF library.


This example creates a NetCDF file and specifies the chunking behavior of a variable.

ncid = netcdf.create('','NETCDF4');
latdimid = netcdf.defDim(ncid,'lat',1800);
londimid = netcdf.defDim(ncid,'col',3600);
varid = netcdf.defVar(ncid,'earthgrid','double',[latdimid londimid]);
netcdf.defVarChunking(ncid,varid,'CHUNKED',[180 360]);


This function corresponds to the nc_def_var_chunking function in the NetCDF library C API.

For copyright information, read the netcdfcopyright.txt and mexnccopyright.txt files.

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