How do I transform a multi-level list into a list of strings in Python?

Question

I have a list that looks something like this:

a = [('A', 'V', 'C'), ('A', 'D', 'D')]

And I want to create another list that transforms a into:

['AVC', 'ADD']

How would I go on to do this?

Answer 1

Use str.join() in a list comprehension (works in both Python 2.x and 3.x):

>>> a = [('A', 'V', 'C'), ('A', 'D', 'D')]
>>> [''.join(x) for x in a]
['AVC', 'ADD']

Answer 2

You could map str.join to each tuple in a:

Python 2:

>>> map(''.join, a)
['AVC', 'ADD']

In Python 3, map is an iterable object so you'd need to materialise it as a list:

>>> list(map(''.join, a))
['AVC', 'ADD']

Answer 3

Using reduce is another option:

>>> a = [('A','V','C'), ('A','D','D')]

In Python 2:

>>> [reduce(lambda x, y: x + y , i) for i in a]
['AVC', 'ADD']

In Python 3 (Thanks for eugene's suggestion):

>>> from functools import reduce
>>> [reduce(lambda x, y: x + y , i) for i in a]
['AVC', 'ADD']