You can use this, fast, gives a tuple:
from Tkinter import _flatten as flatten
-----------------------
The xflatten/flatten version I sometimes use, maybe I can put something
similar in the cookbook, but it can be improved a lot (and isrecursive
is too much fragile):
from pprint import isrecursive
def xflatten(seq, tuplestoo=True, safe=True):
"""xflatten(seq, tuplestoo=True, safe=False): Flattens a sequence,
giving an iterabile. If tupledtoo=True then it flattens tuples
too.
safe=True enables the recursive reference check, do not use it for
too
much nested structures. Examples (iterators):
xflatten( "a" ) ==> ['a']
xflatten( [] ) ==> []
xflatten( [[1,[2,[],"a"]]] ) ==> [1,2,'a']
xflatten( [()] ) ==> []
xflatten( ([[1,[2,[],"a", ()]]],) ) ==> [1, 2, 'a']
xflatten( (12, 34, (11,)) ) ==> (12, 34, 11)
xflatten( (12, 34, (11,)), False ) ==> [(12, 34, (11,))]
Notes on speed:
tuple(xflatten()) is much slower than list(xflatten()).
tuplestoo=False makes this function faster.
safe=True makes this function slower."""
# Modified from: http://google.com/groups?th=957cfbd2e46ac001
if safe and isrecursive(seq):
raise TypeError, "given structure contains a recursive
reference."
if tuplestoo:
if seq.__class__ not in (list, tuple):
yield seq
else:
stack = [iter(seq)]
while stack:
for item in stack[-1]:
if item.__class__ in (list, tuple):
stack.append(iter(item))
break
yield item
else:
stack.pop()
else:
if not seq.__class__ is list:
yield seq
else:
stack = [iter(seq)]
while stack:
for item in stack[-1]:
if item.__class__ is list:
stack.append(iter(item))
break
yield item
else:
stack.pop()
def flatten(seq, tuplestoo=True, safe=True):
# Do not use tuple(xflatten(...)), it's slow.
return list(xflatten(seq, tuplestoo, safe))
Bye,
bearophile
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