How to generate 0 and 1 matrix in specific condition.

Hello everyone. I want to generate a random 4x5 matrix with the elements consist of 0 and 1. But, i don't want each column to have a total amount of 1 that is less than 2. So it's more like:

A =

     0     1     1     1     0
     1     1     1     1     1
     1     1     1     0     1
     0     0     1     0     1

I'm okay if there are 2, 3, or 4 total amount of '1' element, but i don't want even a single column to have only one '1' element, or zero at all. How to make it possible? Thank you very much.

Answer 1

[Matt J]

Using the attached file sortlidx,

m=4; n=15;

A=[ones(1,n);randi([0,1],m-1,n)];

[~,idx]=sortlidx(rand(m,n),1);

A=A(idx)

A = 4×15

0 0 1 1 1 0 1 0 0 1 1 1 0 0 1 1 1 1 0 0 1 0 1 1 1 1 1 1 1 0 0 1 1 0 0 1 1 0 1 1 1 1 1 1 1 0 0 1 1 1 1 0 1 1 1 1 0 1 1 1

[Jenjen Ahmad Zaeni]

Very good. It can be used for many rows and columns quickly. Thank you very much!

Answer 2

[David Hill]

Brute force

a=randi(2,4,5)-1;
while any(sum(a)<2)
    a=randi(2,4,5)-1;
end

[Jenjen Ahmad Zaeni]

Thank you, it works. But i wonder if i can do this to many more column? Lets say it's 50 and 100 column. Because when i tried to change the column to that amount, it keeps loading all the time.