convert vector into 'matrix equivalent'

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J T
J T 2016-10-9
评论： J T 2016-10-9
I have a vector of binomially distributed random numbers from i = 0 to n eg R = [0 1 2 1 4]'
I want to convert this this into a matrix of dimensions length( R ) by n where each row contains either zeros or ones. The number of ones required in each row is taken from the equivalent value in R. Otherwise values are zero. I would like the position of the ones within each row to be random. For instance, if R above and n = 5 then one matrix would be S = [ 0 0 0 0 0; 0 0 1 0 0; 0 1 1 0 0; 0 0 1 0 0; 1 1 1 0 1]
In practice,R is large with 1e6 values so I need the operation to be as fast as possible.
Many thanks!
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Matt J
Matt J 2016-10-9
In practice,R is large with 1e6 values
If m=length( R ) what are the typical magnitudes of both m and n?

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采纳的回答

Walter Roberson
Walter Roberson 2016-10-9
[~, permidx] = sort( rand(length(R), n), 2);
S = permidx <= repmat(R(:),1,n);

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