MATLAB: A better way to change the name of a structure field

Question

Hello,

I would like to change the name of a structure field at run time. Specifically, I want to change all the names to upper case. Currently I am achieving this with the following function:

function s = upperfnames(s)
% upperfnames: converts all the field names in a structure to upper case
    % get the structure field names
    fn = fieldnames(s);
    for ii = 1:length(fn)
        fname = fn{ii};
        % check if the field is already upper case
        if ~strcmp(fname, upper(fname))
            % if not create an upper case copy of the field
            s.(upper(fname)) = s.(fname);
            % and remove the original
            s = rmfield(s, fname);
        end
    end

end

The problem here is that I must create a copy of any fields with names which must be changed. According to the whos function as I step through the code, this uses up double the memory required for the field. This could cause problems when I forget about this in a year or two and try to change the name of a structure containing lots of data. Is there a more memory efficient way of doing this?

Thanks,

Richard

Answer 1

You can use the C-mex function published in the FEX: RenameField

F = fieldnames(S);
S = RenameField(S, F, upper(F));

It creates a shared data copy, such that the memory consumption is minimal.

See also: Loren's Blog

BTW: I get exactly these two links on top, if I ask Google for "Matlab rename field".