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

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amj
amj 2017-11-17
编辑： amj 2017-11-17
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.

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KSSV
KSSV 2017-11-17
X = rand(10,2) ;
idx = randsample(size(X,1),size(X,1)/2) ;
X(idx,:) = NaN
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amj
amj 2017-11-17
编辑：amj 2017-11-17
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

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