Convert list of tuples to list?
PythonPython Problem Overview
How do I convert
[(1,), (2,), (3,)]
to
[1, 2, 3]
Python Solutions
Solution 1 - Python
Solution 2 - Python
@Levon's solution works perfectly for your case.
As a side note, if you have variable number of elements in the tuples, you can also use chain from itertools.
>>> a = [(1, ), (2, 3), (4, 5, 6)]
>>> from itertools import chain
>>> list(chain(a))
[(1,), (2, 3), (4, 5, 6)]
>>> list(chain(*a))
[1, 2, 3, 4, 5, 6]
>>> list(chain.from_iterable(a)) # More efficient version than unpacking
[1, 2, 3, 4, 5, 6]
Solution 3 - Python
Here is another alternative if you can have a variable number of elements in the tuples:
>>> a = [(1,), (2, 3), (4, 5, 6)]
>>> [x for t in a for x in t]
[1, 2, 3, 4, 5, 6]
This is basically just a shortened form of the following loops:
result = []
for t in a:
for x in t:
result.append(x)
Solution 4 - Python
>>> a = [(1,), (2,), (3,)]
>>> zip(*a)[0]
(1, 2, 3)
For a list:
>>> list(zip(*a)[0])
[1, 2, 3]
Solution 5 - Python
You can also use sum function as follows:
e = [(1,), (2,), (3,)]
e_list = list(sum(e, ()))
And it also works with list of lists to convert it into a single list, but you will need to use it as follow:
e = [[1, 2], [3, 4], [5, 6]]
e_list = list(sum(e, []))
This will give you [1, 2, 3, 4, 5, 6]
Solution 6 - Python
>>> a = [(1,), (2,), (3,)]
>>> b = map(lambda x: x[0], a)
>>> b
[1, 2, 3]
With python3, you have to put the list(..) function to the output of map(..), i.e.
b = list(map(lambda x: x[0], a))
This is the best solution in one line using python built-in functions.
Solution 7 - Python
There's always a way to extract a list from another list by ...for...in.... In this case it would be:
[i[0] for i in e]
Solution 8 - Python
Using operator or sum
>>> from functools import reduce ### If python 3
>>> import operator
>>> a = [(1,), (2,), (3,)]
>>> list(reduce(operator.concat, a))
[1, 2, 3]
(OR)
>>> list(sum(a,()))
[1, 2, 3]
>>>
If in python > 3 please do the import of reduce from functools
like from functools import reduce
https://docs.python.org/3/library/functools.html#functools.reduce
Solution 9 - Python
You can also unpack the tuple in the list comprehension:
e = [(1,), (2,), (3,)]
[i for (i,) in e]
will still give:
[1, 2, 3]
Solution 10 - Python
One Liner yo!
list(*zip(*[(1,), (2,), (3,)]))
Solution 11 - Python
In these situations I like to do:
a = [(1,), (2,), (3,)]
new_a = [element for tup in a for element in tup]
This works even if your tuples have more than one element. This is equivalent to doing this:
a = [(1,), (2,), (3,)]
new_a = []
for tup in a:
for element in tup:
new_a.append(element)