do you master list comprehensions?

Fredrik Lundh fredrik at pythonware.com
Tue Dec 14 08:44:10 CET 2004


James Stroud wrote:

> Here is one for arbitrary depth:
>
> def unroll(ary):
>  unrolled = []
>  for item in ary:
>    # add test for your favorite sequence type
>    if ( type(item) == types.ListType or   \
>         type(item) == types.TupleType     \
>       ):
>      unrolled.extend(unroll(item))
>    else:
>      unrolled.append(item)
>  return unrolled
>

>>>> unroll([[1, 2, 3], ('fred', 'barney', ['wilma', 'betty']), 'dino'])
> [1, 2, 3, 'fred', 'barney', 'wilma', 'betty', 'dino']

or, shorter:

>>> from Tkinter import _flatten as unroll
>>> (1, 2, 3, 'fred', 'wilma', 'betty', 'dino')

(alright, it returns a tuple, but that can be easily fixed, if necessary)

</F> 






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