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Specify blocking factor for variable




cdflib.setVarBlockingFactor(cdfId,varNum,blockingFactor) specifies the blocking factor for a variable in a Common Data Format (CDF) file.

Input Arguments


Identifier of a CDF file, returned by a call to cdflib.create or


Numeric value identifying a variable in the file. Variable numbers are zero-based.


Numeric value that specifies the number of records to allocate when writing to an unallocated record.


Create a CDF, create a variable in the CDF, and then set the blocking factor used with the variable. To run this example, you must be in a writable folder.

cdfid = cdflib.create('your_file.cdf');

% Create a variable in the file.
varNum = cdflib.createVar(cdfid,'Time','cdf_int1',1,[],true,[]);

% Get the current blocking factor used with the variable 
bFactor = cdflib.getVarBlockingFactor(cdfid,varNum)

bFactor =


% Change the blocking factor for the variable

% Check the new blocking factor .
bFactor = cdflib.getVarBlockingFactor(cdfid,varNum)

bFactor =


%  Clean up

clear cdfid

More About

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blocking factor

A variable's blocking factor specifies the minimum number of records the library allocates when you write to an unallocated record. If you specify a fractional blocking factor, the library rounds the value down.


This function corresponds to the CDF library C API routine CDFsetzVarBlockingFactor.

To use this function, you must be familiar with the CDF C interface. Read the CDF documentation at the CDF website.

For copyright information, see the cdfcopyright.txt file.

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