Converting a list of lists to a single list

Tue Jul 23 18:49:19 EDT 2013

:
On 23 July 2013 17:52, <steve at divillo.com> wrote:
>> Say I have three lists:
>> [[A0,A1,A2], [B0,B1,B2] [C0,C1,C2]]
>> I would like to convert those to a single list that looks like this:
>[A0,B0,C0,C1,C2,B1,C0,C1,C2,B2,C0,C1,C2,A1,B0,C0,C1,C2,B1,C0,C1,C2,B2,C0,C1,C2,A2,B0,C0,C1,C2,B1,C0,C1,C2,B2,C0,C1,C2]
How's this:
from itertools import chain
def treeify(seq):
 if seq:
 return list(chain(*([x] + treeify(seq[1:]) for x in seq[0])))
 else:
 return []
>>> treeify([['A0', 'A1', 'A2'], ['B0', 'B1', 'B2'], ['C0', 'C1', 'C2']])
['A0', 'B0', 'C0', 'C1', 'C2', 'B1', 'C0', 'C1', 'C2', 'B2', 'C0', 'C1', 'C2',
 'A1', 'B0', 'C0', 'C1', 'C2', 'B1', 'C0', 'C1', 'C2', 'B2', 'C0', 'C1', 'C2',
 'A2', 'B0', 'C0', 'C1', 'C2', 'B1', 'C0', 'C1', 'C2', 'B2', 'C0', 'C1', 'C2']
 -[]z.