Question

Suppose I’m given a struct of arrays, e.g.:

s = 

foo: [3x3 double]
bar: [3x1 double]

Is there an easy way to extract a struct with the same field names as s and with each field populated by the ixth row of the same field in s? I can assume that every field has the same number of rows. Given the above, I could do

ix = 1;
s1.foo = s.foo(ix, :);
s1.bar = s.bar(ix, :);

But if s has more than a couple fields, this gets unwieldy. Is there a function that would do the equivalent, a la s1 = extractstruct(s, ix)?

Answer 1

It s not as short as s1 = extractstruct(s, ix), but I would do that:

s.foo = rand(3);
s.bar = rand(1,3);
xi=1;

s2=reshape([fieldnames(s)'; cellfun(@(x) x(xi,:),struct2cell(s)','UniformOutput',0)],1,[]);
s2=struct(s2{:})


s2 = 

    foo: [0.8147 0.9134 0.2785]
    bar: [0.7922 0.9595 0.6557]