A quick and dirty implementation of Hilbert curves.

hilbert.py

#!/usr/bin/python

from itertools import chain

hilbert = {
    'A': list("-BF+AFA+FB-"),
    'B': list("+AF-BFB-FA+"),
    '-': ['-'],
    '+': ['+'],
    'F': ['F']
}

def iter(n):
    l = ['A']
    i = 0
    while i < n:
        l = chain.from_iterable([hilbert[e] for e in l])
        i = i + 1
    return ''.join(filter(lambda e: e not in ['A', 'B'], l)).replace('+-', '').replace('-+', '')

def perm(n):
    s = iter(n)
    current = 0
    direction = 0
    addends = [1, -2**n, -1, (2**n)]
    ret = [0]
    for c in s:
        if c == 'F':
            current += addends[direction]
            ret.append(current)
        elif c == '+':
            direction = (direction + 1) % 4
        elif c == '-':
            direction = (direction - 1) % 4
        else:
            pass
    return ret

def invert(p):
    ret = [0] * len(p)
    for i,n in enumerate(p):
        ret[n] = i
    return ret