MATLAB Answers

Puzzler for a Monday

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the cyclist
the cyclist on 22 Jul 2013
Commented: David Young on 27 Jan 2015
Given a cell array of strings
A = {'MATLAB','HURRAY','SPARKLY','KITTENS','FUN'};
and a particular string value
B = 'KITTENS';
ensure that B is the last element of the cell array. If it isn't, move it to the end of A.
You cannot assume that B appears at all (in which case return A unchanged), but you can assume B does not appear more than once.
[I have a solution, but I post this as a puzzle because I bet someone can find a slicker one.]

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Answers (6)

Azzi Abdelmalek
Azzi Abdelmalek on 22 Jul 2013
idx=strcmp(A,B)
out=[A(~idx) A(idx)]

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the cyclist
the cyclist on 22 Jul 2013
Here's mine:
[~,idx] = sort(ismember(A,B));
A = A(idx)

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Sean de Wolski
Sean de Wolski on 22 Jul 2013
idx = ismember(A,B);
C = cat(isrow(A)+1,A(~idx),A(idx))

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Evan
Evan on 22 Jul 2013
Awesome. I especially like the "isrow" trick. I'll be remembering that one.

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Evan
Evan on 22 Jul 2013
Edited: Evan on 22 Jul 2013
Here's my solution. It's ugly, but I think it's fairly general. :P
function A = cell_shuffle(A)
idx = cellfun(@(x)isequal(B,x),A);
A = [A(~idx) A(idx)];
end
This would make for a nice CODY problem, by the way.

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Abdullah Caliskan
Abdullah Caliskan on 27 Jan 2015
k=ismember(A,B) A(k)='' if sum(k)==0 A=A; else A=[A B] end

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David Young
David Young on 27 Jan 2015
[~, idx] = ismember(B, A);
C = circshift(A, [0 -idx]);

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David Young
David Young on 27 Jan 2015
Note: does not preserve the ordering of the other elements.

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