使用MATLAb随机选择矩阵中30％的元素

Question

I need to do the following for each of elements of a matrix of size mXn: 1. flip a coin with a 0.3 probability of success. 2. if its a success set the element to zero. 3. else move to the next element.

I used the following code, but it does not give any output and produces NaN, C is the matrix of size mXn:

index = (rand(size(C)<=0.3));
one_index = find(index ==1);
C(one_index) = 0;

Answer 1

The problem is this statement

index = (rand(size(C)<=0.3));

You've messed up the parentheses so you're trying to compare if size(C) <= 0.3 . This returns [0 0] , causing rand to create an empty matrix.

Also, the call to find is unnecessary.

C = magic(4);
index = rand(size(C)) <= 0.3;
C(index) = 0

C =

    16     2     3    13
     0    11    10     8
     9     7     6     0
     4     0    15     1