How to randomly select an array of 20 nonrepeating values from another array which has 100 values with positive or negative values.

How to randomly select an array of 20 nonrepeating values from another array which has 100 values with positive or negative values inside.

Answer 1

[David Hill]

a=randi(200,1,100)-100;
SelectArray=a(randperm(100,20));

Answer 2

[Md Nazmul Hoque]

like lets say,

its a 3*20 matrix i want to generate, from 3*100 matrix,

i want to select 20 random column, but that 20 random column's corrospending row should not be changed.

[Torsten]

N = randperm(100);
N = sort(N(1:20));
a = a(:,N);