Matlab-reading large netcdf files - matlab

Question

I have a 17G netcdf file that I am trying to use for analysis. Each variable in the netcdf file is set up like: variable(x,y,z,time). I would like to read in and analyze the variables one 'time' at a time for analysis in Matlab. In other words, I want to use all x, y, and z points at one time. In the past I have had smaller files so reading in a variable has been set up like
fid=netcdf.open('filename/location','NC_NOWRITE');
var_id=netcdf.inqVarID(fid,'varname');
var=netcdf.getVar(fid,var_id);
Is it possible to read in the variables using one time step when the variable is read in? (Incorrect syntax) It'd essentially look like
var=netcdf.getVar(fid,var_id,[:,:,:,time_index]);

Answer 1

Yes, the matlab netcdf command supports this, almost the way you wrote it:
data = netcdf.getVar(fid,var_id,var_index,var_length)
See the matlab documentation for more information. You can also use high-level matlab commands instead of the netCDF library functions.
For example, if varname is a 100x4 array, you could get row 7 by using:
% read 4 columns from 1 row of data starting at row 7, column 1
v = ncread('filename/location','varname',[7 1],[1 4]);
or a four-dimensional array, as in the question:
% read all data from dim. 1-3 at dim 4 = 27
v = ncread('filename/location','varname',[1 1 1 27],[Inf Inf Inf 1]);