如何在matlab中显示randperm（）是公平的

假设，我想（从经验上）证明，来自matlab的randperm（n，k）确实从一组n个元素中产生大小为k的均匀分布随机样本。重复绘制后，如何绘制出现次数除以从N中绘制的k-子集总数的曲线？

您可以简单地使用从

randperm

中绘制的索引来增加计数器向量

n=1e5;
k=1e4;
maxiter = 1e5;

% This array will be used to count the number of times each integer has been drawn
count=zeros(n,1);

for ii=1:maxiter
    p=randperm(n,k);
    % p is a vector of k distinct integers in the 1:n range
    % the array count will be incremented at indices given by p
    count(p)=count(p)+1;
end

% A total of k*maxiter integers has been drawn and they should be evenly
% distributed over n values
% The following vector should have values close to 1 for large values of maxiter
prob = count*n/(k*maxiter);

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您可以简单地使用从

randperm

中提取的索引来增加计数器向量

n=1e5;
k=1e4;
maxiter = 1e5;

% This array will be used to count the number of times each integer has been drawn
count=zeros(n,1);

for ii=1:maxiter
    p=randperm(n,k);
    % p is a vector of k distinct integers in the 1:n range
    % the array count will be incremented at indices given by p
    count(p)=count(p)+1;
end

% A total of k*maxiter integers has been drawn and they should be evenly
% distributed over n values
% The following vector should have values close to 1 for large values of maxiter
prob = count*n/(k*maxiter);