Python split for lists
itertools.groupby is one approach (as it often is):
>>> l = ["data","more data","","data 2","more data 2","danger","","date3","lll"]
>>> from itertools import groupby
>>> groupby(l, lambda x: x == "")
<itertools.groupby object at 0x9ce06bc>
>>> [list(group) for k, group in groupby(l, lambda x: x == "") if not k]
[['data', 'more data'], ['data 2', 'more data 2', 'danger'], ['date3', 'lll']]
We can even cheat a little because of this particular case:
>>> [list(group) for k, group in groupby(l, bool) if k]
[['data', 'more data'], ['data 2', 'more data 2', 'danger'], ['date3', 'lll']]
One possible implementation using itertools
>>> l
['data', 'more data', '', 'data 2', 'more data 2', 'danger', '', 'date3', 'lll']
>>> it_l = iter(l)
>>> from itertools import takewhile, dropwhile
>>> [[e] + list(takewhile(lambda e: e != "", it_l)) for e in it_l if e != ""]
[['data', 'more data'], ['data 2', 'more data 2', 'danger'], ['date3', 'lll']]
Note*
This is as fast as using groupby
>>> stmt_dsm = """
[list(group) for k, group in groupby(l, lambda x: x == "") if not k]
"""
>>> stmt_ab = """
it_l = iter(l)
[[e] + list(takewhile(lambda e: e != "", it_l)) for e in it_l if e != ""]
"""
>>> t_ab = timeit.Timer(stmt = stmt_ab, setup = "from __main__ import l, dropwhile, takewhile")
>>> t_dsm = timeit.Timer(stmt = stmt_dsm, setup = "from __main__ import l, groupby")
>>> t_ab.timeit(100000)
1.6863486541265047
>>> t_dsm.timeit(100000)
1.5298066765462863
>>> t_ab.timeit(100000)
1.735611326163962
>>>
reduce
comes to mind:
def split(iterable, where):
def splitter(acc, item, where=where):
if item == where:
acc.append([])
else:
acc[-1].append(item)
return acc
return reduce(splitter, iterable, [[]])
data = ["data","more data","","data 2","more data 2","danger","","date3","lll"]
print split(data, '')
Result:
[['data', 'more data'], ['data 2', 'more data 2', 'danger'], ['date3', 'lll']]
I'm not sure wether this is the most "pythonic" way of solving it.
def split_seq(seq, sep):
start = 0
while start < len(seq):
try:
stop = start + seq[start:].index(sep)
yield seq[start:stop]
start = stop + 1
except ValueError:
yield seq[start:]
break
ll = ["data","more data","","data 2","more data 2","danger","","date3","lll"]
p = [i for i in split_seq(ll,"")]