Turn logical matrix into string vector
显示 更早的评论
Hi. I have the logical matrix idx and the string array vec.
idx = logical([0 1 0; 0 0 1; 1 0 0; 1 0 0; 0 1 0])
vec = ["A","B","C"]
Each row of idx indicates which letter (from vec) should be assigned to that row.
The desired result is:
result = ["B";"C";"A";"A";"B"]
Is there a way to 'apply' matrix idx to a string matrix, or something like the following:
temp = repmat(vec, [size(idx,1), 1])
temp(idx) %This returns something but not as expected
采纳的回答
idx = logical([0 1 0; 0 0 1; 1 0 0; 1 0 0; 0 1 0])
vec = ["A","B","C"]
vec(idx(:,1)*1 + idx(:,2)*2 + idx(:,3) * 3).'
vec(idx*(1:size(idx,2)).').'
更多回答（3 个）
Assuming idx has one 1 per row
idx = logical([0 1 0; 0 0 1; 1 0 0; 1 0 0; 0 1 0]);
vec = ["A","B","C"];
[r,c]=find(idx);
result(r)=vec(c)
Yvan Lengwiler
2021-5-9
(I wrote my answer as a comment above. Sorry. Here it is as a formal answer.)
Of course, even if a solution does not appear to use a loop as seen in the Matlab program code, there will be a loop in the ultimapte machine code anyway. Not having a code in the Matlab program can improve legibility of the text for humans, but it is not obvious that it improves the speed of execusion.
Anyway, here is a solution:
idx = logical([0 1 0; 0 0 1; 1 0 0; 1 0 0; 0 1 0]);
vec = ["A","B","C"];
tempvec = repmat(vec', [size(idx',2), 1]);
tempidx = idx'; tempidx = tempidx(:);
result = tempvec(tempidx)'
2 个评论
Walter Roberson
2021-5-9
Seems over-complicated compared to
vec(idx*(1:size(idx,2)).').'
Yvan Lengwiler
2021-5-9
True :-)
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