randperm

Random permutation

Usage

p = randperm(n)

• It returns a random permutation (shuffling) of the vector 1:n, where n is a real integer $\geq 1$.

p = randperm(n, k)

• It returns a row vector of k unique integers taken from the vector 1:n, where k is an integer such that 1 <= k and k <= n hold.

Examples

• randperm gives the same output when the random number generator is initialized with the same seed..

Input

% Initalize the random number generator with seed 0.
rng(0)
randperm(6)
randperm(6,5)

% Initalized with the same seed.
% randperm gives the same results as before.
rng(0)
randperm(6)
randperm(6,5)

Output

ans = 
 2.0000   6.0000   4.0000   1.0000   3.0000   5.0000

ans = 
 2.0000   4.0000   1.0000   6.0000   3.0000

ans = 
 2.0000   6.0000   4.0000   1.0000   3.0000   5.0000

ans = 
 2.0000   4.0000   1.0000   6.0000   3.0000

Discussions

• When the built-in random number generator is initialised with the same seed, randperm gives the same permutation.
• Since this app's algorithms for generating random numbers and initial states may be different from MATLAB's, users should not expect this app and MATLAB to give the same sequences of pseudo-random numbers.