How to find a specific row in the matrix and extract it to the new matrix

Question

Moe 2015-3-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/181137-how-to-find-a-specific-row-in-the-matrix-and-extract-it-to-the-new-matrix

编辑： Andrei Bobrov 2015-3-2

Can anyone give me any suggestion how I can find the specific row (matrix= criteria) from main matrix (big matrix) and then extract to the some sub-matrices (A, B, C)

Z = [1  1  1  2
2  3  1
1  3  4
2  1  3
1  1  2
2  3  1
1  3  4
1  1  2
2  3  1
1  3  4
1  1  2
2  1  3
2  1  3
2  1  3
2  3  1
1  3  4
2  1  3
1  1  2
1  1  2
2  3  1
2  3  1
1  3  4
1  1  2
2  1  3
2  1  3
2  3  1
1  3  4]
M = [1  1  2
3  1
3  4]

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Azzi Abdelmalek 2015-3-2

What is your criterion

Moe 2015-3-2

编辑：Moe 2015-3-2

Criteria is the second matrix in the photo.

For example I need to find all of rows in the first matrix that according to the "A" criteria has [1 1 2]. Therefore, output should be same as third matrix:

[1  1  1  2
1  1  2
1  1  2
1  1  2
1  1  2
1  1  2
1  1  2]

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Answer 1

Andrei Bobrov 2015-3-2

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https://ww2.mathworks.cn/matlabcentral/answers/181137-how-to-find-a-specific-row-in-the-matrix-and-extract-it-to-the-new-matrix#answer_169860

编辑：Andrei Bobrov 2015-3-2

Z = [1 1 1 2
2 3 1
1 3 4
2 1 3
1 1 2
2 3 1
1 3 4
1 1 2
2 3 1
1 3 4
1 1 2
2 1 3
2 1 3
2 1 3
2 3 1
1 3 4
2 1 3
1 1 2
1 1 2
2 3 1
2 3 1
1 3 4
1 1 2
2 1 3
2 1 3
2 3 1
1 3 4];
M = [1 1 2
3 1
3 4];
[l,i0] = ismember(Z(:,2:end),M,'rows');
zz = Z(l,:);
out = accumarray(i0(l),(1:nnz(i0))',[],@(x){sortrows(zz(x,:))});

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Answer 2

Guillaume 2015-3-2

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https://ww2.mathworks.cn/matlabcentral/answers/181137-how-to-find-a-specific-row-in-the-matrix-and-extract-it-to-the-new-matrix#answer_169859

Use ismember with the 'rows' option:

ismatchrow = ismember(Z(:, 2:end), M(1, :), 'rows');
A = Z(ismatchrow, :)

Or to obtain a cell array with all the submatrices:

[~, matchrow] = ismember(Z(:, 2:end), M, 'rows');
matches = cell(1, max(matchrow));
for m = 1:max(matchrow)
   matches{m} = Z(matchrow == m, :);
end
celldisp(matches)

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Answer 3

Star Strider 2015-3-2

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This works:

[Zu, ia, ic] = unique(Z(:,2:4), 'rows');
[Lia,Locb]  = ismember(M,Zu,'rows');
for k1 = 1:size(M,1)
    R{k1} = find(Locb(k1) == ic);
end
A = Z(R{1},:);
B = Z(R{2},:);
C = Z(R{3},:);