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How can I delete rows in a matrix where two numbers exist side-by-side?

조회 수: 1(최근 30일)
sravan
sravan 2014년 3월 18일
답변: Jos (10584) 2014년 3월 18일
I have a large matrix that has thousands of rows.
I need to delete the rows based on the following condition:
>>> if in a row, ith column is 2 and (i+1)th column is 3
e.g. Input matrix [1, 2, 1; 1, 2, 1; 2, 2, 3]
Expected output: [1,2,1;1,2,1]

채택된 답변

lvn
lvn 2014년 3월 18일
This should do the job. If you have a huge matrix and you want it to go faster, you will need to adapt this code to build up a vector with all rows that need deleting and do that once only (at the end).
A=[2,7,3;1, 2, 1; 1, 2, 1; 2, 2, 3; 1, 2, 1; 2, 3, 4]
rows=1;
while rows<=length(A)
if strfind(A(rows,:),[2 3])
A(rows,:)=[];
end
rows=rows+1;
end
A
Output:
A =
2 7 3
1 2 1
1 2 1
2 2 3
1 2 1
2 3 4
A =
2 7 3
1 2 1
1 2 1
1 2 1

추가 답변(1개)

Jos (10584)
Jos (10584) 2014년 3월 18일
A = [2,7,3;1, 2, 1; 1, 2, 1; 2, 2, 3; 1, 2, 1; 2, 3, 4]
i = 1:size(A,2)-1
tf = A(:,i)==2 & A(:,i+1)==3 % true if i-the column is 2 and (i+1)th column is 3
A(any(tf,2),:) = [] % remove those rows

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