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Matlab struct with names and sizes of the mat.file

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Robert Bag
Robert Bag on 12 May 2021
Commented: Walter Roberson on 13 May 2021
Hi, I am trying to create a function that asks for mat.file and then I would like t o create a struct which returns the name and size of the variables in the mat.file.
Anyone who knows how to do that?

Answers (1)

Walter Roberson
Walter Roberson on 12 May 2021
Use whos() with the '-file' option and extract the required data from that.
Walter Roberson
Walter Roberson on 13 May 2021
whos() is built-in, so I cannot look at the source code for it. There is no documented way to get whos() to only display specified fields.
But why are you asking about displaying fields? Your question and comments indicate that you want the information returned as a struct with field 'name' and 'size' . Displaying is a different task.
The below code has been constructed to mimic the output of whos. It might have some fine details wrong about automatic sizing or justification of field widths.
function info = fileinfo(filename)
if ~exist(filename, 'file')
error(message('MATLAB:whos:fileIsNotThere', filename));
tinfo = whos('-file', filename);
if nargout > 0
info = struct('name', {}, 'size', {tinfo.size});
fields = ["name", "size"; "", ""; string({}.'), cellfun(@(S) strjoin(arrayfun(@string,S),'x'), {tinfo.size}.')];
L = strlength(fields);
widths = max(L,[],1);
fmt = compose(" %%-%ds %%-%ds", max([14, 0], widths));
fprintf('%s\n', compose(fmt, fields(:,1), fields(:,2)))

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