MATLAB: Selecting specific layers in the 3rd dimension of a matric

matrix manipulation

Hi, I have a matrix A of size 226 x 621 x 59. May I know how do I form a new matrix of A[:,:,(43;53)] – selecting only the 43-53rd layers in the 3rd dimension, and then finding the mean of the 11 layers, eventually forming a 2d matrix of the means?

Thank you, appreciate any help given 🙂

Best Answer

squeeze(mean(A(:,:,43:53)))

Related Solutions

MATLAB: Mean of 3rd dimension

A = [1 2 3; 4 5 6; 7 8 9];
A(:,:,2) = [10 11 12; 13 14 15; 16 17 18];
A(:,:,3) = [19 20 21; 22 23 24; 25 26 27];
A(:,:,3) = [28 29 30; 31 32 33; 34 35 36];
meanA = mean(A(:,:,1:2),3);

Take a look at this exampl. This will help you out!

also you should see the function "mean":

https://www.mathworks.com/help/matlab/ref/mean.html?searchHighlight=mean&s_tid=doc_srchtitle&requestedDomain=

MATLAB: Looping through 3rd dimension

Your loop has 19 iterations. It is not clear, why you expect that the output has a size of 30 or 540 in the 3rd dimension.

[i:i] is the same as the much simpler: i .

A simplified version of your code:

ST = T(:, :, 30:48)

No loop needed. But I do not see, how this could produce a size of 30 or 540.

By the way, this can be simplified also:

ST=NaN*ones(128,64,30)
% Better:
ST = NaN(128, 64, 30)

But it is not useful here, so better omit it.

[EDITED] After the clarifications:

ST  = NaN(128, 64, 18, 30);  % Pre-allocate
ini = 30;
len = 18;
for k = 1:30
    ST(:, :, :, k) = T(:, :, ini:ini + len - 1);
    ini = ini + 72;
end
ST = reshape(ST, 128, 64, 540);
% Or:
v     = 1:72;
match = (30 <= v & v < 48);
ST    = T(:, :, repmat(match, 1, 30));

Best Answer

Related Solutions

MATLAB: Mean of 3rd dimension

MATLAB: Looping through 3rd dimension

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