Dimension error in matrix manipulation

2011 8 31
2 个回答
回答已采纳
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0 个投票

Hi, trying to figure out why this doesn't work and how to make it work:-
looktime2= [1 16; 2 55; 2 61; 2 66; 2 68; 5 20; 6 60; 8 47; 8 83; 8 105; 9 72; 10 44; 10 57]
t2 = [true;diff(looktime2(:,1))~=0]; t2 = [t2,looktime2(:,2)];
t2 = [1 16; 1 55; 0 61; 0 66; 0 68; 1 20; 1 60; 1 47; 0 83; 0 105; 1 72; 1 44; 0 57]
Rmatrix is a 10 by 121 matrix
for i = 1:size(t2,1)
for j = 1
if t2(i,j)==1
sd(i,j) = Rmatrix(looktime2(i,j),1:t2(i,j+1));
end
if t2(i,j)==0
sd(i,j) = Rmatrix(looktime2(i,j),t2(i-1,j+1):t2(i,j+1));
end
end
end
When I press enter I get an Subscripted assignment dimension mismatch error , but I'm not sure how to get it to work.
Any help will be much appreciated. Thanks

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 采纳的回答

Andrei Bobrov
Andrei Bobrov 2011-8-31

0 个投票

variant 1 (use 'arrayfun')
t = [true;diff(looktime2(:,1))~=0];
idx = [0;looktime2(1:end-1,2)];
idx(t)=1;
idx2 = [idx looktime2(:,2)];
di = diff(idx2,1,2)+1;
sd = arrayfun(@(i1)[Rmatrix(looktime2(i1),idx2(i1,1):idx2(i1,2)) zeros(1,max(di)-di(i1))],1:numel(t),'un',0);
sd=cat(1,sd{:});
variant 2 (use loop)
t = [true;diff(looktime2(:,1))~=0];
idx = [0;looktime2(1:end-1,2)];
idx(t)=1;
idx2 = [idx looktime2(:,2)];
di = diff(idx2,1,2)+1;
nt = numel(t);
sd = zeros(nt,max(di));
for i1 = 1:nt
sd(i1,1:di(i1)) = Rmatrix(looktime2(i1),idx2(i1,1):idx2(i1,2));
end
variant 3 (vectorization with use 'bsxfun')
l=looktime2';
t = [true diff(l(1,:),1,2)~=0];
idx = [0,l(2,1:end-1)].*~t+t;
di = diff([idx; l(2,:)])+1;
mdi = max(di);
sdt = zeros(mdi,numel(t));
sz = size(Rmatrix);
lm = bsxfun(@and,bsxfun(@le,(1:sz(2))',l(2,:)),bsxfun(@ge,(1:sz(2))',idx));
i1=bsxfun(@times,lm,l(1,:));
j1 = bsxfun(@times,(1:sz(2))',lm);
sdt(bsxfun(@le,(1:mdi)',di)) = Rmatrix(sub2ind(sz,i1(lm), j1(lm)));
sd = sdt';
variant 4 (your variant)
looktime2= [1 16; 2 55; 2 61; 2 66; 2 68; 5 20; 6 60; 8 47; 8 83; 8 105; 9 72; 10 44; 10 57];
t2 = [true;diff(looktime2(:,1))~=0];
t2 = [t2,looktime2(:,2)];
%t2 = [1 16; 1 55; 0 61; 0 66; 0 68; 1 20; 1 60; 1 47; 0 83; 0 105; 1 72; 1 44; 0 57]
%Rmatrix is a 10 by 121 matrix
sd = nan(size(Rmatrix));
for i1 = 1:size(t2,1)
if t2(i1,1)
k = 1:t2(i1,2);
sd(i1,1:numel(k)) = Rmatrix(looktime2(i1,1),k);
else
k = t2(i1-1,2):t2(i1,2);
sd(i1,1:numel(k)) = Rmatrix(looktime2(i1,1),k);
end
end
sd = sd(:,~all(isnan(sd)));

更多回答（1 个）

zohar
zohar 2011-8-31

0 个投票

Hi Amandeep,
This is the problem
sd(i,j) = Rmatrix(looktime2(i,j),1:t2(i,j+1));
Subscripted assignment dimension mismatch.
Rmatrix(looktime2(i,j),1:t2(i,j+1)) is vector , and sd(i,j) is 1x1 you can not do that.
Have fun

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