How to assign few of the array values with a constant randomly .

I try with randperm but not getting an idea.

suppose n=10 and m=4;

require array with value '1' in 4 random position from 1 to 10 and othe postions value '0;

Expected result,

i.e array =[1, 0, 0, 1, 0, 0, 0, 0, 1,1] here m=4 and n=10

[madhan ravi]

"I try with randperm but not geeting idea.„

Why?

Answer 1

[Stephen23]

"How to assign few of the array values with a constant randomly ."

>> n = 10;
>> m = 4;
>> V = zeros(1,n);  % generate array
>> X = randperm(n); % random indices
>> V(X(1:m)) = 1    % assign constant to some elements
V =
  0  0  1  0  1  0  0  1  1  0

[chandra Naik]

Thank you, it works as i expected.

[chandra Naik]

Dear Stephen Cobeldick,

With continution with previous question,

Require array with value '1' in 4 random position from 1 to 10 and othe postions value '0;

Expected result,

i.e array =[1, 0, 0, 1, 0, 0, 0, 0, 1,1] here m=4 and n=10

Suppose two array values associated with m , say Xm and Ym (a point on a plane)

i.e Xm=[20,25,30,25] %X axis coordinate

Ym=[18,23,30,25] %Y axis coordinate,

then how to get corresponding array values Xm and Ym with respect to

[1, 0, 0, 1, 0, 0, 0, 0, 1,1]

i.e Xm_new=[20, 0, 0, 25, 0, 0, 0, 0, 30,25]

Ym_new=[18, 0, 0, 23, 0, 0, 0, 0, 30,25]

I trying with loops, if better approach could you share your thought.

Thank you

Answer 2

[KALYAN ACHARJYA]

m=4;n=6;
A=[ones(1,m) zeros(1,n)];
[rows colm]=size(A);
colm_data=randperm(colm);
result=A(:,colm_data)

Please do change according as per your requirements (Minor Change)

Answer 3

[chandra Naik]

Problem resolved using soution of Stephen Cobeldick,

valuesX=zeros(1,n);

valuesY=zeros(1,n);

values = zeros(1,n); % generate array

X = randperm(n); % random indices

values(X(1:m)) = 1 % assign constant to some elements

disp(X);

valuesX(X(1:m))=Xm % assign Xm values

valuesY(X(1:m))=Ym % assign Ym values