Question about using randperm in a loop
2 次查看(过去 30 天)
显示 更早的评论
Hi,
I'm using randperm in a loop that's meant to generate unique random three-digit numbers to fill a 5x5 matrix, r, like this:
for i = 1:length(r)
r(1:5,i) = (randperm(900,5) + 99);
end
My question is:
Is there a possibility of repeating a number given the function is being called 5 times, once for each column? I want each number to be unique.
Thanks,
Veena
0 个评论
采纳的回答
John D'Errico
2020-3-10
编辑:John D'Errico
2020-3-10
So, you want to sample 5 sets of 5 numbers, all from the same set, but you want them to be unique? (The technical description would be to sample without replacement.)
The point is, you already know how to sample 5 such numbers. So just sample 25 numbers!
r = reshape(randperm(900,25) + 99,[5 5]);
There is no reason to need a loop.
更多回答(1 个)
James Tursa
2020-3-10
编辑:James Tursa
2020-3-10
If you want each number in the matrix to be unique, then don't call randperm( ) by row because that will not guarantee uniqueness between calls. Call randperm( ) only once for the entire matrix (25 elements) and then reshape to a 5x5. E.g., something like
r = reshape(randperm(900,25) + 99,5,5);
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Logical 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!