How can I subtract columns for each row by using a for loop
조회 수: 7 (최근 30일)
이전 댓글 표시
Hi,
I have a matrix like this:
[1.011 1.004 1.054
1.008 0.998 1.042
0.984 0.988 1.024
1.026 1.006 1.016
1.000 0.996 0.977]
I would like to subtract each column for each row and store these results in a new matrix. How can I do this?
Thanks!
댓글 수: 2
Joseph Cheng
2014년 9월 29일
can you expand on what you mean by subtract each column for each row? I do not understand what you're subtracting with.
채택된 답변
추가 답변 (3개)
Joseph Cheng
2014년 9월 29일
편집: Joseph Cheng
2014년 9월 29일
you can use combnk() or nchoosek to determine the combination of column subtraction and perform a for loop for each combination.
X = randi(10,4,3);
combin = combnk(1:size(X,2),2);
for ind = 1:size(X,2)
newX(:,ind) = X(:,combin(ind,1))-X(:,combin(ind,2));
end
댓글 수: 0
Guillaume
2014년 9월 29일
Use nchoosek to get all possible combinations of columns, and use that to calculate your differences:
m = [1.011 1.004 1.054
1.008 0.998 1.042
0.984 0.988 1.024
1.026 1.006 1.016
1.000 0.996 0.977];
colcomb = nchoosek(1:size(m, 2), 2);
coldiff = zeros(size(m, 1), size(colcomb, 1));
for comb = 1:size(colcomb, 1)
coldiff(:, comb) = diff(m(:, colcomb(comb, :)), 1, 2);
end
댓글 수: 7
dpb
2014년 9월 29일
For what working definition of small? But, basic idea is one of two choices...
a) go ahead and generate all pairs and then compute the comparison statistic and choose the N smallest of those, or,
b) compute each pair and the statistic at same time; after N replace the largest of those kept with the last if new is less; update the maxValue comparison value.
Andrei Bobrov
2014년 9월 30일
편집: Andrei Bobrov
2014년 9월 30일
X = [1.011 1.004 1.054
1.008 0.998 1.042
0.984 0.988 1.024
1.026 1.006 1.016
1.000 0.996 0.977];
n = nchoosek(1:size(X,2),2);
out = squeeze(diff(reshape(X(:,n'),[],2,3),1,2));
댓글 수: 0
참고 항목
카테고리
Help Center 및 File Exchange에서 Logical에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!