Fast generation of permutations

[Anton Vredegoor]

Paul Rubin wrote:

>     def deals():
>         for i in xrange(13**5):
>             cards = [(i//p) % 13 for p in (1, 13, 169, 2197, 28561)]
>             yield cards

This gives hands like [0,0,0,0,1] and [0,0,0,1,0] which are
permutations of one another.

Below is a piece of code that avoids this. Here's how to interprete its
output. Suppose one gets a hand like [0,1,2,3,4]. This means that it
would be possible to create 1024 (4**5) poker hands from this, by
"coloring" the cards.

Another hand, for example [0,0,1,2,3], would allow only 384 colorings,
because the two zeros would contribute choose 2 out of 4 (colors), so 6
colorings. The other numbers remain available for 4 colorings, which
gives 6*4**3 (==384) colorings for this hand.

Similar things happen for other partionings of the hands into numbers.
In fact I am now investigating a description based on integer
partitions  of the number 5. I am not sure whether I want to partition
based on colors or on numbers, that seems to arbitrary.

This is very fascinating. Maybe someday I'll make a tkinter script with
a visual tree structure allowing all kinds of numbers of "cards", and
arbitrary numbers of variables to partition by.

This would then give result sets like those strange quantum particles,
such as quarks.

Have fun,

Anton

def hands(L = [0]):
    if len(L) == 6:
        if L[1] != L[-1]: #no five of a kind
            yield L[1:]
    else:
        for i in range(L[-1],13):
            for H in hands(L+[i]):
                yield H

def pprint(i,hand):
    print '%5i:   ' %i,
    for x in hand:
        print '%2i ' % x,
    print

def test():
    H = hands()
    total = 0
    for i,x in enumerate(H):
        pprint(i,x)

if __name__=='__main__':
    test()