question about expanding an index
in [Matlab]
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From: Bruno Luong on 17 Jun 2010 17:02 "Matt Fig" <spamanon(a)yahoo.com> wrote in message <hve28s$33d$1(a)fred.mathworks.com>... > Single line indeed! I knew there was an accumarray solution in there somewhere, but I will cop to dpb's excuse! Oh common, you guys are hopeless about admiring the poesy of accumarray. I'm going to sleep. Bruno
From: Matt Fig on 17 Jun 2010 17:07 "Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message <hve2gc$ht6$1(a)fred.mathworks.com>... > "Matt Fig" <spamanon(a)yahoo.com> wrote in message <hve28s$33d$1(a)fred.mathworks.com>... > > > Single line indeed! I knew there was an accumarray solution in there somewhere, but I will cop to dpb's excuse! > > Oh common, you guys are hopeless about admiring the poesy of accumarray. I'm going to sleep. > > Bruno There is a problem with A(end) = 0, if the solution is to be that general. I am sure you see the fix!
From: Bruno Luong on 18 Jun 2010 11:02 "Matt Fig" <spamanon(a)yahoo.com> wrote in message <hve2po$6op$1(a)fred.mathworks.com>... > There is a problem with A(end) = 0, if the solution is to be that general. I am sure you see the fix! A fix that prevails a single-line is not quite straight-forward but possible. y = subsref(cumsum(accumarray(cumsum([1; A(:,2)]), diff([0; A(:,1); inf]))),substruct('()',{1:sum(A(:,2))})) Bruno
From: Bruno Luong on 18 Jun 2010 11:25 > % Engine > nz = A(:,2)~=0; > idx = A(nz,1); > CS = cumsum(A(nz,2)); > y = zeros(CS(end),1); > y([1; CS(1:end-1)+1]) = 1; > y = idx(cumsum(y)) Matt, any quick fix for A=[1 0;2 0] ??? Attempted to access CS(0); index must be a positive integer or logical. Bruno
From: Matt Fig on 18 Jun 2010 12:54
"Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message > Matt, any quick fix for A=[1 0;2 0] > > ??? Attempted to access CS(0); index must be a positive integer or logical. > > Bruno Always the danger in pointing out a flaw in Bruno's code! ;') It seem like a little IF check would need to be put in. |