concatenate structs in a loop

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S
S on 6 May 2011
I have a 1x7 struct, each containing the same number of rows but differing number of columns. I want to concatenate each struct into a new matrix but was wondering if I can do this in a loop?
For example, A is a 1x7 struct containing data B. I essentially want to do:
cat(2,A(1,1).B, A(1,2).B, A(1,3).B, A(1,4).B, A(1,5).B, A(1,6).B, A(1,7).B)
but in a loop. Is this possible? Thanks in advance.

Accepted Answer

Matt Fig
Matt Fig on 6 May 2011
A 1-by-n structure, where the data in each n has the same number of rows but different number of columns:
A(1,1).B = [5.5 4.5;5.5 4.5];
A(1,2).B = [6.3 4.3 3.3;6.3 4.3 3.3];
A(1,3).B = [7.1 2.1 3.1 4.1;7.1 2.1 3.1 4.1];
Here is one way to do it in a loop:
G = cell(1,length(A));
for ii = 1:length(A)
G{ii} = A(ii).B;
end
G = [G{:}];
Or, simply (as Walter also pointed out):
G2 = cat(2,A(:).B); % isequal(G,G2)==1

More Answers (1)

Paulo Silva
Paulo Silva on 6 May 2011
for n=1:size(A,1)
s{n}=cat(2,A(n,1).B, A(n,2).B, A(n,3).B, A(n,4).B, A(n,5).B, A(n,6).B, A(n,7).B);
end
  2 Comments
S
S on 6 May 2011
Hi Paulo, first of all, thank you for the reply.
I should have been a bit more clear. I'd like to have it so that matlab recognizes how many structs are there and fills in the A1, A2, A3 ... An in the concatenate function. So if I have struct 1x7, I'd like to have matlab execute cat(2,A1,A2,A3,A4,A5,A6,A7) but if I had a struct 1x5, do cat(2,A1,A2,A3,A4,A5), if struct 1x8, then cat(2,A1,A2,A3,A4,A5,A6,A7,A8). Is this possible? Thanks again for your help.
S

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