matrix, where each element is a column vector

Question

Alessandro 2024-5-4

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https://ww2.mathworks.cn/matlabcentral/answers/2115036-matrix-where-each-element-is-a-column-vector

评论： Image Analyst 2024-5-4

Excuse me, I need some help. I have an 11*7 matrix. Each element of this matrix consists of a column vector 1001*1. I want to calculate for each column matrix the maximum value. thanks for your help

ETATT=cell(11,7); % initial matrix

Etat=zeros(1001,1); % column vector, contained in each element of the ETATT matrix

I want to find the maximum value of each Etat contained in ETATT

THANKS

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Stephen23 2024-5-4

Please upload your data in a MAT file, by clicking the paperclip button.

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Answer 1

John D'Errico 2024-5-4

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编辑：John D'Errico 2024-5-4

在 MATLAB Online 中打开

You don't need a cell array at all!

Just use a 3-d array.

A = randn(11,7,1001);

Now to compute the max in each vector, just use max.

Amax = max(A,[],3)
Amax = 11x7
8855    3.1273    3.4970    3.4644    3.2119    3.3252    3.3440
5491    3.4246    3.0522    3.0026    3.6090    2.8491    3.1710
8150    3.1949    2.8692    3.1197    2.9194    3.7617    3.4712
7289    3.5455    3.3983    3.9485    3.6122    3.3107    3.0513
6401    2.9991    3.3636    4.0458    3.6022    2.7523    2.8631
3276    3.4824    3.3375    3.1679    2.9176    3.4002    2.8746
8566    2.8198    3.1635    3.1104    2.9772    2.5777    3.4800
4694    3.9244    3.4734    2.8729    3.0262    2.9374    3.0426
3679    3.0261    3.2774    2.9603    3.1238    2.9358    3.1946
9948    3.6696    3.7775    2.9491    3.1029    3.2715    3.2116
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You can extract any vector from Amax simply enough.

v = Amax(i,j,:);

This will be a 1x1x1001 vector. If you want it to be a true column vector, then just do

v = squeeze(A(i,j,:));

Or, you can store the array as a 1001x11x7 array. Now you can extract the (i,j) vector as

V = rand(1001,11,7);
V(:,1,2)
ans = 1001x1
    0.7608
    0.4326
    0.0963
    0.5112
    0.7267
    0.8622
    0.7442
    0.4668
    0.3008
    0.5712
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Image Analyst 2024-5-4

John's absolutely right. Don't complicate things by using a cell array if you don't have to, and from what you've said so far, it doesn't appear you have to.

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Answer 2

the cyclist 2024-5-4

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https://ww2.mathworks.cn/matlabcentral/answers/2115036-matrix-where-each-element-is-a-column-vector#answer_1452261

在 MATLAB Online 中打开

ETATT=cell(11,7); % initial matrix
Etat=zeros(1001,1); % column vector, contained in each element of the ETATT matrix
% Fill each cell with a random column vector
for ii=1:11
for jj=1:7
    ETATT{ii,jj} = rand(1001,1);
end
end
% Find the max of each vector
maxEtat = cellfun(@max,ETATT);