How to convert list list to single list without import

Question

My list:

a = [[1,2], [23,51,6], ["Hi", "hello"]]

I want to release:

a = [ 1,2,23 51,6, "Hi", "hello"]

Answer 1

Using list comprehension :

>>> a = [[1,2], [23,51,6], ["Hi", "hello"]]
>>> [x for xs in a for x in xs]
[1, 2, 23, 51, 6, 'Hi', 'hello']

Answer 2

Use sumwith two arguments, a list of lists, and an empty list to add:

>>> sum(a, [])
[1, 2, 23, 51, 6, 'Hi', 'hello']

what really is a special case reduce:

>>> reduce(list.__add__, a)
[1, 2, 23, 51, 6, 'Hi', 'hello']

, , Guido reduce Python 3 , ( ). sum , reduce . Python 3 reduce.

, itertools.chain, , . list, :

>>> import itertools
>>> list(itertools.chain(*a))
[1, 2, 23, 51, 6, 'Hi', 'hello']

Answer 3

itertools.chain.from_iterable:

>>> from itertools import chain
>>> a = [[1,2], [23,51,6], ["Hi", "hello"]]
>>> list(chain.from_iterable(a))
[1, 2, 23, 51, 6, 'Hi', 'hello']

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