Merging a list of lists

Question

How do I merge a list of lists?

[[\'A\', \'B\', \'C\'], [\'D\', \'E\', \'F\'], [\'G\', \'H\', \'I\']]

into

[\'A\', \'B\', \         


        

Answer 1

Don't use sum(), it is slow for joining lists.

Instead a nested list comprehension will work:

>>> x = [['A', 'B', 'C'], ['D', 'E', 'F'], ['G', 'H', 'I']]
>>> [elem for sublist in x for elem in sublist]
['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I']
>>> ['' + elem + '' for elem in _]

The advice to use itertools.chain was also good.