permutations

perm.jl

@doc "All length `n` permutations of `v` in a matrix, with repetitions."->
function perm_matrix{T}(v::Vector{T}, n)
  l = length(v)
  m = l^n
  a = Array(T, m, n)
  for i = 1:m
    k = i-1
    j = n
    while (j > 0)
      (d,r) = divrem(k,l)
      a[i,j] = v[r+1]
      k = d
      j -= 1
    end
  end
  a
end

function permuted_combinations{T}(v::Vector{T},k)
  l = length(v)
  m1 = binomial(l,k)
  m2 = factorial(k)
  a = Array(T, m1*m2, k)
  j = 0
  for c in combinations([2,3,5],2)
    for p in permutations(1:k)
      j += 1
      a[j,:] = c[p]
    end
  end
  a
end