varnum = cdflib.createVar(cdfId, varname, datatype, numElements, dims, recVariance, dimVariance) creates a new variable in the Common Data Format (CDF) file with the specified characteristics.

Input Arguments

cdfId

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

varname

Text string that specifies the name you want to assign to the variable.

datatype

Data type of the variable. One of the following text strings, or its numeric equivalent, that specifies a valid CDF data type.

CDF Data Type Description

CDF_BYTE 1-byte, signed integer

CDF_CHAR 1 byte, signed character data type that maps to the MATLABchar class

CDF_INT1 1-byte, signed integer

CDF_UCHAR 1 byte, unsigned character data type that maps to the MATLABuint8 class

CDF_UINT1 1-byte, unsigned integer

CDF_INT2 2-byte, signed integer

CDF_UINT2 2-byte, unsigned integer

CDF_INT4 4-byte, signed integer

CDF_UINT4 4-byte, unsigned integer

CDF_FLOAT 4-byte, floating point

CDF_REAL4 4-byte, floating point

CDF_REAL8 8-byte, floating point.

CDF_DOUBLE 8-byte, floating point

CDF_EPOCH 8-byte, floating point

CDF_EPOCH16 two 8-byte, floating point

numElements

Number of elements per datum. Value should be 1 for all data types, except CDF_CHAR and CDF_UCHAR.

dims

A vector of the dimensions extents; empty if there are no dimension extents.

recVariance

Specifies record variance: true or false.

dimVariance

A vector of logicals; empty if there are no dimensions.

Output Arguments

varNum

The numeric identifier for the variable. Variable numbers are zero-based.

Examples

Create a CDF file and then create a variable named 'Time' in the CDF. The variable has no dimensions and varies across records. To run this example, you must be in a writable folder.

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

% Initially the file contains no variables.
info = cdflib.inquire(cdfid)

info = 

     encoding: 'IBMPC_ENCODING'
     majority: 'ROW_MAJOR'
       maxRec: -1
      numVars: 0
    numvAttrs: 0
    numgAttrs: 0

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

% Retrieve info about the file again to verify variable was created. 
% Note value of numVars field is now 1.
info = cdflib.inquire(cdfid)

info = 

     encoding: 'IBMPC_ENCODING'
     majority: 'ROW_MAJOR'
       maxRec: -1
      numVars: 1
    numvAttrs: 0
    numgAttrs: 0

% Clean up
cdflib.delete(cdfid);

clear cdfid

References

This function corresponds to the CDF library C API routine CDFcreatezVar. To use these functions, you must be familiar with the CDF C interface. Read the CDF documentation at the CDF Web site. For copyright information, see the cdfcopyright.txt file.