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A better way to change the name of a structure field?

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Richard Crozier
Richard Crozier on 17 Mar 2011
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);
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?


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Accepted Answer

Jan on 17 Mar 2011
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".


Richard Crozier
Richard Crozier on 17 Mar 2011
I'd googled things like 'Matlab change structure field name', but not the word 'rename' at any point. That just brought up the matlab doc links which do not have info on this. I'll have to try harder on my google word choices in future :-)
Jan on 17 Mar 2011
And I will insert your searched words as tags in the FEX page.

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