Simple cartesian product

[Magnus L. Hetland]

Just wondered if anyone had a simple and elegant little snippet that
returns the cartesian products of two lists... for-loops and append is
a simple solution, but not very "cool" ;)

I have a *nearly* finished function:

def product(a,b):
    a = 
    b = b * len(a)
    return map(None, a, b)

What I'm missing here is a simple expression which will make a list
like [1, 2, 3, 4] into [1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4] (if
len(b)==3)...

(Of course, all of this is a breeze with list comprehension ;)

--

  Magnus
  Lie
  Hetland