Select random elements from three consecutive columns in a big matrix?
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Hello all,
I have a 12 by 12 matrix, and I want to select 10 random elements. The elements should be from only three consecutive columns.
For example, I want to use 10 random elements from columns (1, 2, 3) or they could be from columns (2, 3, 4) or columns(3, 4, 5) and so on.
Any help please.
Thanks
3 Comments
Guillaume
on 5 Apr 2019
Edited: Guillaume
on 5 Apr 2019
Please do not ask the same question twice.
Duplicate of https://www.mathworks.com/matlabcentral/answers/454534-select-elements-from-only-three-consecutive-columns
And it looks like you delete your question once answered, which is not going to go down well with us (and will be restored anyway).
Answers (2)
Walter Roberson
on 5 Apr 2019
N = 10;
[r, c] = size(YourMatrix);
start_col = randi([1, c-2]);
chosen = YourMatrix(start_col * r - 1 + randi([1 3*r], 1, N));
Jos (10584)
on 5 Apr 2019
Edited: Jos (10584)
on 5 Apr 2019
M = magic(5) % input data
N = 4 % number of selections
nC = 3 % number of consecutive columns
% engine
szM = size(M)
r = randi(szM(1), N, nC) % N x 3 random rows
c = randi(szM(2) - nC + 1, N, 1) % N random first columns
c = c + [0:nC-1] % add consecutive columns
R = M(sub2ind(szM, r, c)) % index into M
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