Replace all instances of a value with random number

I am currently trying to replace all instances of the value 1 in an array with a different random number.

For example, if I have

A = [1 0 1 0;
     0 1 0 0;
     1 0 0 0;
     1 1 0 1];

then I want a simple piece of code to quickly get something like:

A = 0.7144  0      0.1217 0;
     0      0.9840 0      0;
     0.5931 0      0      0;
     0.2695 0.4320 0      0.9305];

I have tried using A(A==1)=rand but that filled in all of the 1s with th same random number.

I know this would be really easy to do using for loops but I am keen to avoid this because the A array will get quite large and end up being a drag on the performance of the overall script.

Answer 1

[Jeremy]

A = [0 1 0 1; 1 0 1 1; 0 0 1 1];
id = A==1;
r = rand(1,nnz(id));
A(id) = r;

[ME]

Awesome, thank you!