i have 16 different types of files and i have to take the files in the bunch of 2 from the 16 files, how i put permutation and combination to get 2 files from the 16 files each time differently?

please keep in mind 1 and 2 is different combination and 2 and 1 is different combination.

Answer 1

[Guillaume]

Since there are only 240 combinations, it's trivial to generate them all as a 240x2 matrix:

allperms = nchoosek(1:16, 2);
allperms = [allperms; fliplr(allperms)];

You can then choose a row at random:

oneperm = allperms(randi(size(allperms, 1)), :)

or shuffle all the rows

allperms = allperms(randperm(size(allperms, 1)), :)

[Sun Heat]

thanks soo much....it's work but if we change the bunch of material to 3 or 4 then this code works universally to all

[Sun Heat]

i think it works.

[Guillaume]

No, It does not extend to more than two elements. A generic version:

v = 1:16;
n = 4;

allperms = nchoosek(v, n);  %all combinations
colperms = num2cell(perms(1:n), 2);  %how many ways can we swap the columns
allperms = cell2mat(cellfun(@(p) allperms(:, p), colperms, 'UniformOutput', false))  %swap the columns all possible ways

[Sun Heat]

this is universal code for n number of combination.