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# random matrix with a given number of specified elements

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sko on 3 Aug 2020
Commented: sko on 3 Aug 2020
Hello,
How can we generate a matrix n x n Whose elements can be only two values AND where number of one of those two elements is given?
For instance, in the 3 x 3 matrix elements can be only 0 et 1, But I want exactly 4 elements to be zeros (and therefore 5 elements to be ones)
Thank you

#### 2 Comments

madhan ravi on 3 Aug 2020
Did you try something for your homework ?
sko on 3 Aug 2020
I only did research on random numbers generation but I didn’t find the answer on the second part of my needs i.e. specifying the number (amount) of a given element (number).

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### Accepted Answer

madhan ravi on 3 Aug 2020
Edited: madhan ravi on 3 Aug 2020
v = [repelem(1, 5), repelem(0, 4)];
Wanted = v(reshape(randperm(numel(v)), 3, []))

#### 1 Comment

sko on 3 Aug 2020
Thank you very much.
This is what I need!
Best wishes

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### More Answers (1)

Bruno Luong on 3 Aug 2020
Edited: Bruno Luong on 3 Aug 2020
User inputs
matsz = [3,3];
n1 = 4; % number of desired 1s, no need to specify for 0s
Generate
B = zeros(matsz); % + 0;
B(randperm(numel(B),n1)) = 1;
Quick check
B

#### 1 Comment

sko on 3 Aug 2020
This works too!
Thank you very much.

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R2017b

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