Break a big matrix into cell array based on repetitive number in one of the matrix columns

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Mori 2016-7-24

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https://ww2.mathworks.cn/matlabcentral/answers/296936-break-a-big-matrix-into-cell-array-based-on-repetitive-number-in-one-of-the-matrix-columns

评论： Star Strider 2016-7-24

I have a matrix of 383533*3 doubles, column 2 includes some repetitive numbers, like 2.5483e+06 here, which is similar for 600 raw. how I can break down this big matrix into cells which each cell includes 3 columns of numbers which second column is constant for each cell.

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Answer 1

Star Strider 2016-7-24

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This approach works:

M = randi(9, 20, 3);                                % Create Data
M(1:9,2) = ones(9,1)*3;                             % Create Data
M(10:end,2) = ones(11,1)*7;                         % Create Data
[U2,ia,ic] = unique(M(:,2));                        % Unique Values In Column #2
rows = accumarray(ic, 1);                           % Lengths Uf Unique Values
Result = mat2cell(M, rows, size(M,2));              % Cell Array Of Separated Matrices

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Mori 2016-7-24

nice thanks.

Star Strider 2016-7-24

Thank you. My pleasure!

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Answer 2

Azzi Abdelmalek 2016-7-24

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https://ww2.mathworks.cn/matlabcentral/answers/296936-break-a-big-matrix-into-cell-array-based-on-repetitive-number-in-one-of-the-matrix-columns#answer_229599

在 MATLAB Online 中打开

%------Example---------------
A(1:1000,[1 3])=randi(100,1000,2)
A(:,2)=randi(3,1000,1)
%-----The code-----------------
[ii,jj,kk]=unique(A(:,2))
out=accumarray(kk,(1:numel(kk))',[],@(x) {A(x,:)})