How to efficiently replace value at the n last column?
조회 수: 1 (최근 30일)
이전 댓글 표시
Dear all, The objective was to replace the value at the end of a column. I have make a simple case but wonder if there is another way to make it more compact and efficient?
Thanks in advance
f_sbj=2
sA=23;
A =1:sA;
appndOut=cell(sA,1);
for f_x=1:sA
Out = nchoosek(A, f_x);
[rows, columns] = find(Out==f_sbj);
Out(rows, :) = [];
[m,n] = size(Out );
newNan=nan(m,(sA-n));
appndOut{f_x}=[newNan Out];
end
댓글 수: 2
Walter Roberson
2018년 9월 4일
That code appears to insert at the beginning of columns, not replace at the end of columns.
The code can be made more compact, but not necessarily more efficient.
채택된 답변
Walter Roberson
2018년 9월 4일
lastNcol = @(M, N) M(:,end-N+1:end);
NanPrePad = @(M, N) lastNcol( [nan(size(M,1), N), M], N);
select_and_prepad = @(M, N) NanPrePad( M(all(M~=f_sbj, 2),:) );
appndOut = arrayfun(@(f_x) select_and_prepad(nchoosek(A, f_x), sA), (1:sA).', 'uniform', 0);
You can use shorter names for the anonymous functions if you find the above to not be compact enough.
Though I wonder why you do not do something like
A = setdiff(1:sA, f_sbj);
That would eliminate the possibility of f_sbj being generated by the nchoosek, so it would not be necessary to delete any rows containing f_sbj.
댓글 수: 3
Walter Roberson
2018년 9월 4일
f_sbj=2
sA=23;
A =1:sA;
lastNcol = @(M, N) M(:,end-N+1:end);
NanPrePad = @(M, N) lastNcol( [nan(size(M,1), N), M], N);
select_and_prepad = @(M, N) NanPrePad( M(all(M~=f_sbj, 2),:), N );
appndOut = arrayfun(@(f_x) select_and_prepad(nchoosek(A, f_x), sA), (1:sA).', 'uniform', 0);
This takes a moment to execute.
추가 답변 (0개)
참고 항목
카테고리
Help Center 및 File Exchange에서 Get Started with MATLAB에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!