# Extracting data from struct as matrix

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Rashi Monga el 13 de Jun. de 2024
Comentada: Stephen23 el 14 de Jun. de 2024
Hi,
I have the following struct:
S(1).a = 1:5;
S(2).a = 11:10;
S(3).a = 21:27;
Is there a way to vertically concatenate them without looping? I cannot do vertcat(S.a) because data is of different size.
I want output like this [1:5; 11:10; 21:27]
Thank you
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Ganesh el 13 de Jun. de 2024
A matrix with these dimensions cannot be constructed.
a = [1:5; 11:10; 21:27]
Error using vertcat
Dimensions of arrays being concatenated are not consistent.
Stephen23 el 13 de Jun. de 2024
"I want output like this [1:5; 11:10; 21:27]"
Matrices cannot have rows of different lengths.

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Ganesh el 13 de Jun. de 2024
You can consider the following workaround for your problem, without using for loops:
S(1).a = 1:10;
S(2).a = 11:17;
S(3).a = 21:26;
aCell = arrayfun(@(x) {x.a}, S);
% Find the maximum length among all arrays
maxLength = max(cellfun(@numel, aCell));
% Function to pad arrays with NaN to match the maxLength
padFunction = @(x) [x, NaN(1, maxLength - numel(x))];
y = cellfun(padFunction, aCell, 'UniformOutput', false);
y = vertcat(y{:})
y = 3x10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 NaN NaN NaN 21 22 23 24 25 26 NaN NaN NaN NaN
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Rashi Monga el 13 de Jun. de 2024
Thanks everyone for their replies. It was helpful.
Stephen23 el 14 de Jun. de 2024
and use it like this:
S(1).a = 1:5;
S(2).a = 10:11;
S(3).a = 21:27;
M = 3x7
1 2 3 4 5 NaN NaN 10 11 NaN NaN NaN NaN NaN 21 22 23 24 25 26 27
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### Más respuestas (2)

Jonas el 13 de Jun. de 2024
Editada: Jonas el 13 de Jun. de 2024
as you already said, you canot concatenate the data as matrix, since it has different size. you could use a cell array, but this would be no better than the struct. another possibility coul be to pad shorter variables with NaN. but here, you would need a loop.
S(1).a = 1:5;
S(2).a = 11:10;
S(3).a = 21:27;
sizes=arrayfun(@(in) length(in.a),S);
maxSize=max(sizes);
asMatrix=nan(numel(sizes),maxSize);
for sNr=1:numel(S)
asMatrix(sNr,1:sizes(sNr))=S(sNr).a;
end
asMatrix
asMatrix = 3x7
1 2 3 4 5 NaN NaN NaN NaN NaN NaN NaN NaN NaN 21 22 23 24 25 26 27
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Shivani el 13 de Jun. de 2024
Editada: Shivani el 13 de Jun. de 2024
You will need to modify the solution in the above answer as seen in the below code snippet to obtain the desired result.
S(1).a = 1:5;
S(2).a = 11:15;
S(3).a = 21:25;
M = vertcat(S.a)
M = 3x5
1 2 3 4 5 11 12 13 14 15 21 22 23 24 25
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Please note that the ranges you have provided cannot be concatenated vertically because they will not be of the same length. I am therefore assuming the ranges to be 1:5, 11:15 and 21:25. Since they all contain 5 elements, we can concatenate them to a matrix containing 5 columns.
Hope this helps!
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