How to create NaN randomly based on specific rate in specific column

Hi,

I'm going to create NaN values in a data set. I found this basic code, but it is not specify for which column.

X = rand(10,2)
p = randperm(numel(X))
%p1 = randperm(X)
randel = p(1:5)
X(p(1:5)) = NaN

This is my code which is able to set NaN in the second column only: Y = rand(10,2) ratioNan=0.5 Y(rand(size(X(:,1)))<=ratioNan,2)=NaN

This code does not produces the result as expected. For instance, if i want to set the 50% NaN values, sometime it is created more or less than 50% of the records. How to change the code so that i will remove exactly 50% from the record specifically in the second column.

Answer 1

[KSSV]

X = rand(10,2) ;

idx = randsample(size(X,1),size(X,1)/2) ;

X(idx,:) = NaN

[amj]

Dear KSSV,

Thanks a million for your answer. I also just resolved the problem. This is my answer:

x = rand(20,2);
idx = randperm(20);
x(idx(1:5),2) = NaN