how to extract nested lists? [duplicate]

Answer 1

An alternative solution to using itertools.chain would be:

>>> li = [["a","b","c"], ["d","e","f"], ["g","h","i","j"]]
>>> chained = []
>>> while li:
...     chained.extend(li.pop(0))
... 
>>> chained
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j']

EDIT: The above example will consume your original lists while building the new one, so it should be an advantage if you are manipulating very large lists and want to minimise memory usage. If this is not the case, I would consider using itertools.chain more pythonic way to achieve the result.