How can I access all field elements of a structure array nested in a cell array in MATLAB?

Question

Here's code that creates an example cell array for this question:

mycell = cell([5,1]);
for i = 1 : size(mycell)
    mystruct = struct();
    mycell{i} = mystruct;
    mycell{i}.field1 = i;
end

I expected mycell{:}.field1 to do what I want, but it gives an error. I can use the following for loop:

for i = 1 : size(mycell)
    mycell{i}.field1
end

but I'd prefer a simpler or more elegant solution as a want to use all the elements of mycell.field1 as the y-variables in a plot. Any ideas?

Community · Accepted Answer · 2017-05-23 12:03:05Z

16

Two possible solutions:

If all the structs in your cell array have the same fields than you can:

mycell = [ mycell{:} ]; % convert cell array to struct array
y = [ mycell(:).filed1 ]; % get the values

Another method uses cellfun

y = cellfun( @(x) x.field1, mycell );

assuming all mycell{ii}.filed1 are scalars, otherwise you'll need to add 'UniformOutput', false to the cellfun.

note: in case some fields are empty ([]) these methods might not work as expected.

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answered Feb 14, 2013 at 19:52

Shai

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Thanks for the note about i and j. I have definitely found debugging to be easier now that I'm not using them as for loop counters.

Unfortunately, the structs do not have all the same fields. The cellfun method worked beautifully! Thanks.