Create Unique Randomsample 1000 times
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Hi Everyone,
I want to create a matrix based on 1000 random samples of 50 numbers selected from 1 to 100, as follows:
a = [];
for i =1:n
y = randsample(100,50);
a = horzcat(a,sort(y));
end
Here the variable "a" should have 1000 fields for 50 random numbers selected from 1 to 100
I want to make sure that the numbers are unique for each field. Does anyone know the best way to do this?
Thanks
回答（2 个）
a = zeros(n, 50);
for i =1:n
a(i, :) = sort(randsample(100,50));
end
[EDITED] Or do you mean that the rows should be guaranteed to be different? Then:
% Rejection method:
a = zeros(n, 50);
i = 0;
while i < n
v = sort(randperm(100, 50));
if ~any(all(a(1:i, :) == v, 2))
i = i + 1;
a(i, :) = v;
end
end
Akira Agata
2017-8-17
Just in case, you can check the uniqueness by:
% Make a variable 'a'
a = zeros(1000, 50);
for i =1:1000
a(i, :) = sort(randsample(100,50));
end
% Check the uniqueness
isUnique = true(1000,1);
for i =1:1000
if length(unique(a(i,:))) ~= 50
isUnique(i) = false;
end
end
any(~isUnique)
2 个评论
Steve Sous
2017-8-21
Akira Agata
2017-8-22
Well, I don't understand your point clearly.
In my previous code, each row of a contains unique 50 random number. That means length(unique(a(k,:))) is always 50 for all k (=1:1000). Therefore, even if you add the line "a(10,:) = a(1,:);", the output any(~isUnique) becomes 0 and there is no strange point in this behavior.
So, I would be happy if you could explain clearly what is the point and what kind of output you want to obtain.
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