# How to concatenate matrices when some of them can be empty?

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Leon on 15 Dec 2021
Commented: Leon on 15 Dec 2021
I have 10 matrices, each of them would either have a size of n by 12, or is empty. For example: T1 can be a matrix with a size of 100 x 12, but it can also be []. The same thing goes true for T2, ... T10.
What is the best way to put them together like the below?
vertcat(T1, T2, T3, ... T10)
Many thanks!

Image Analyst on 15 Dec 2021
I'd do it almost like you. This works fine and has 9 rows because T7 is empty.
T1 = rand(1, 12);
T2 = rand(1, 12);
T3 = rand(1, 12);
T4 = rand(1, 12);
T5 = rand(1, 12);
T6 = rand(1, 12);
T7 = [];
T8 = rand(1, 12);
T9 = rand(1, 12);
T10 = rand(1, 12);
tallerMatrix = vertcat(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)

Voss on 15 Dec 2021
make the empty matrices 0-by-12, then you can vertcat them like normal.
if isempty(T2)
T2 = zeros(0,12);
end
% and so on
Leon on 15 Dec 2021
Many thanks!
Interesting to hear the behavior of zeros when vertcating.

R2021b

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