Rotate vector in row
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Nikoleta
le 12 Jan 2020
Commenté : Adam Danz
le 15 Jan 2020
Hi, i have an array
n= [1,19,15,18,21,10,16,2,7,3,17,6,1;
1,14,20,8,4,13,9,5,1,0,0,0,0;
1,11,12,1,0,0,0,0,0,0,0,0,0];
What i need to do is to randomly choose 2 elements of each row (but not the ones and the zeros) and rotate the vector in between them .
For example new_n= [ 1,19,15,17,3,7,2,16,10,21,18,6,1;
1,14,13,4,8,20,9,5,1,0,0,0,0;
1,12,11,1,0,0,0,0,0,0,0,0,0]
If it is possible i would like to be able to do it for any array i might have. (the thing is that 1-etc-1 in each row are non equal paths that start at depot 1 and end at it after they go through the other nodes, so i want the rearrangement to happen between the depots)
4 commentaires
Adam Danz
le 12 Jan 2020
I see. The next point that needs clarifying is ,"'randomly choose 2 elements of each row (but not the ones and the zeros) ",
Does that mean that any value can be chosen except 1s and 0s or does it mean that the vector between the two end points must not include any 1s and 0s?
For example, is it OK if these two points are chosen?
[0 0 0 0 9 8 7 6 5 4 3 2 1 1 1 1 2 3 4]
% ^...........^
Réponse acceptée
Thiago Henrique Gomes Lobato
le 12 Jan 2020
This may solve your problem:
rng(42)
n= [1,19,15,18,21,10,16,2,7,3,17,6,1;
1,14,20,8,4,13,9,5,1,0,0,0,0;
1,11,12,1,0,0,0,0,0,0,0,0,0];
nrev = n;
for idx=1:size(n,1)
% Get the position of the initial 0
Ncolums = find(n(idx,:)==0);
if isempty(Ncolums)
Ncolums = size(n,2);
else
Ncolums = Ncolums(1)-1;
end
Ncolums = Ncolums-2; % Remove first and last 1
% Get a random index permutation between valid index
Index = randperm(Ncolums)+1; % Add offset so it starts by two
Index = sort(Index(1:2));
% Invert row
nrev(idx,Index(1):Index(2)) = n(idx,Index(2):-1:Index(1));
end
nrev
nrev =
1 19 15 18 21 10 16 6 17 3 7 2 1
1 14 20 8 13 4 9 5 1 0 0 0 0
1 12 11 1 0 0 0 0 0 0 0 0 0
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Adam Danz
le 12 Jan 2020
Modifié(e) : Adam Danz
le 12 Jan 2020
Simpler
n= [1,19,15,18,21,10,16,2,7,3,17,6,1;
1,14,20,8,4,13,9,5,1,0,0,0,0;
1,11,12,1,0,0,0,0,0,0,0,0,0];
% randomly choose 2 elements of each row
% (but not the ones and the zeros)
randIdx = arrayfun(@(i)sort(randsample(find(~ismember(n(i,:),[1,0])),2)),1:size(n,1),'UniformOutput',false);
% rotate the vector in between each index, per row
for i = 1:size(n,1)
n(i, randIdx{i}) = fliplr(n(i, randIdx{i}));
end
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