%% Import CDF Files Using Low-Level Functions
% This example shows how to use low-level functions to read data from a CDF file. The MATLAB® low-level CDF functions correspond to routines in the CDF C API library. To use the MATLAB CDF low-level functions effectively, you must be familiar with the CDF C interface.
%% Open CDF File
% Open the sample CDF File, example.cdf.

cdfid = cdflib.open('example.cdf');

%
%% Get Information About File Contents
% Use cdflib.inquire to get information about the number of variables in the file, the number of global attributes, and the number of attributes with variable scope.

info = cdflib.inquire(cdfid)

%
%% Get Information About Variables
% Use cdflib.inqurieVar to get information about the individual variables in the file. Variable ID numbers start at zero.

info  = cdflib.inquireVar(cdfid,0)

%

info  = cdflib.inquireVar(cdfid,1)

%
%% Read Variable Data Into Workspace
% Read the data in a variable into the MATLAB workspace. The first variable contains CDF Epoch time values. The low-level interface returns these as double values.

data_time = cdflib.getVarRecordData(cdfid,0,0)

%
% Convert the time value to a date vector.

timeVec = cdflib.epochBreakdown(data_time)

%
%% Read Global Attribute From File
% Determine which attributes in the CDF file are global.

info = cdflib.inquireAttr(cdfid,0)

%
% Read the value of the attribute. You must use the  cdflib.getAttrgEntry function for global attributes.

value = cdflib.getAttrgEntry(cdfid,0,0)

%
%% Close CDF File
% Use cdflib.close to close the CDF file.

cdflib.close(cdfid);

% Copyright 2015 The MathWorks, Inc.