combinations of variable length nested lists
aleax at aleax.it
Wed Aug 8 14:04:30 CEST 2001
"xauau" <xauau at yahoo.com.au> wrote in message
news:840bdd8f.0108080216.6dffdbc9 at posting.google.com...
> def permute(a):
> if len(a) == 0: return []
> return [[x] + y for x in a for y in permute(a[1:])]
> Actually, it needs all of three lines if you count the func def ;-)
> Just for fun, does anyone know how to move the 'if' into the list
> comprehension to make it a one-liner?
It's easy to oneline this function's body _without_ moving
the test inside the list comprehension (it's a long line
so my newsreader might break it, but it's logically one):
return (len(a)==0 and []) or [[x]+y for x in a for y in permute(a[1:])]
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