How to remove rows contain 0 in matrix

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Alex Rob
Alex Rob 2017-3-8
回答： Akira Agata 2017-3-15
Assume matrix A as follows:
A = [1 1 2 2 3 3
10 10 7 10 9 5
5 45 4 15 1 10
1 50 3 30 5 65
6 55 1 0 8 90
2 0 2 0 2 0
3 0 5 0 3 0
4 0 6 0 4 0
7 0 8 0 6 0
8 0 9 0 7 0
9 0 10 0 10 0
];
I want to remove rows contain 0 and make new matrix B. In the matrix B, the first column is unique ID which are repeated based on matrix A (first row).
B = [1 10 10
1 5 45
1 1 50
1 6 55
2 7 10
2 4 15
2 3 30
2 3 3
2 9 5
2 1 10
2 5 65
2 8 90
];

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回答（3 个）

dpb
dpb 2017-3-8
The first part seems pretty easy, but I've no klew how you actually got B from what's left...in fact, there are several elements retained that don't show up at all if the rows containing zero are removed--the 8,90 values for just one case.
>> A(all(A,2),:)
ans =
1 1 2 2 3 3
10 10 7 10 9 5
5 45 4 15 1 10
1 50 3 30 5 65
>>
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dpb
dpb 2017-3-12
OK, had some time to try to deduce how the output was produced...other than there's an error in the original in that the first row [3 3] values were included initially that was most confusing as well as the indices didn't include 1:3 but 1:2, I think what you're looking for is (given the last A as starting point)--
>> [As,iA]=sort(A(:,2:4)); % Sort columns exclusive of index
>> nR=sum(As>0); % find how many are in each column excluding zeros
>> ix=find(As>0); % indices nonzeros locations in column-major order
>> B=[cell2mat(arrayfun(@(n,c) repmat(c,n,1),nR.',[1:length(nR)].','uniform',0)) iA(ix) As(ix)]
B =
1 10 10
1 5 45
1 1 50
1 6 55
2 7 10
2 4 15
2 3 30
3 9 5
3 1 10
3 5 65
3 8 90
>>
Akira Agata
Akira Agata 2017-3-15
Maybe I could understand what you want. To clarify, I wrote the code in step-by-step manner. I hope this matches to what you want to do.
A = [1 50 0 10
2 0 0 0
3 0 30 0
4 0 15 0
5 45 0 65
6 55 0 0
7 0 10 0
8 0 0 90
9 0 0 5
10 10 0 0
];
idx = A(:,2) == 0;
B1 = [sortrows(A(~idx,[1 2]),2); sortrows(A(idx,[1 2]),1)];
idx = A(:,3) == 0;
B2 = [sortrows(A(~idx,[1 3]),2); sortrows(A(idx,[1 3]),1)];
idx = A(:,4) == 0;
B3 = [sortrows(A(~idx,[1 4]),2); sortrows(A(idx,[1 4]),1)];
% Now, [B1 B2 B3] is the matrix B in Alex's post on 8 Mar 2017 at 22:01.
% Extract the target columns
C = [B1(:,1) B2(:,1) B3(:,1)];

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