How to show that randperm() in matlab is fair
Suppose, I wanted to show (empirically) that randperm(n,k) from matlab indeed produces uniformly distributed random samples of size k from a set N of n elements. How can I plot the number of occurences divided by the total number of k-subsets drawn from N, after drawing repeatedly?
matlab probability combinatorics
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
add a comment |
Suppose, I wanted to show (empirically) that randperm(n,k) from matlab indeed produces uniformly distributed random samples of size k from a set N of n elements. How can I plot the number of occurences divided by the total number of k-subsets drawn from N, after drawing repeatedly?
matlab probability combinatorics
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
add a comment |
Suppose, I wanted to show (empirically) that randperm(n,k) from matlab indeed produces uniformly distributed random samples of size k from a set N of n elements. How can I plot the number of occurences divided by the total number of k-subsets drawn from N, after drawing repeatedly?
matlab probability combinatorics
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
Suppose, I wanted to show (empirically) that randperm(n,k) from matlab indeed produces uniformly distributed random samples of size k from a set N of n elements. How can I plot the number of occurences divided by the total number of k-subsets drawn from N, after drawing repeatedly?
matlab probability combinatorics
matlab probability combinatorics
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
asked Nov 23 '18 at 9:24
Christian SingerChristian Singer
125210
125210
add a comment |
add a comment |
1 Answer
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You can simply use the indices drawn from randperm to increment a counter vector.
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);
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
@Ander Biguri done
– Brice
Nov 23 '18 at 11:33
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You can simply use the indices drawn from randperm to increment a counter vector.
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);
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
@Ander Biguri done
– Brice
Nov 23 '18 at 11:33
add a comment |
You can simply use the indices drawn from randperm to increment a counter vector.
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);
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
@Ander Biguri done
– Brice
Nov 23 '18 at 11:33
add a comment |
You can simply use the indices drawn from randperm to increment a counter vector.
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);
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
You can simply use the indices drawn from randperm to increment a counter vector.
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);
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
edited Nov 23 '18 at 11:32
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
answered Nov 23 '18 at 9:34
BriceBrice
1,400110
1,400110
@Ander Biguri done
– Brice
Nov 23 '18 at 11:33
add a comment |
@Ander Biguri done
– Brice
Nov 23 '18 at 11:33
@Ander Biguri done
– Brice
Nov 23 '18 at 11:33
@Ander Biguri done
– Brice
Nov 23 '18 at 11:33
add a comment |
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