Transform list of arrays

Question

I'm new to python. How is possible to transform an array like this:

x=[[0.3], [0.07], [0.06]]

into:

x=[0.3,0.07, 0.06]

? Thanks in advance.

score 5 · Accepted Answer · edited May 23 '17 at 12:04

5

The following list comprehension may be useful.

>>> x=[[0.3], [0.07], [0.06]]
>>> y = [a for [a] in x]
>>> y
[0.3, 0.07, 0.06]

Considering that the inner values are of type list too.

A similar but more readable code, as given by cdhowie is as follows.

>>> x=[[0.3], [0.07], [0.06]]
>>> y = [a[0] for a in x]
>>> y
[0.3, 0.07, 0.06]

edited May 23 '17 at 12:04

Community

answered Apr 29 '13 at 16:23

Sukrit Kalra

2

Or `y = [a[0] for a in x]`, which is equivalent, assuming that the input elements are lists and not some other indexable object. – cdhowie Apr 29 '13 at 16:24
Yeah. That is an equivalent method too. You mind if I tag you and include that in the answer? Might be helpful for other people. – Sukrit Kalra Apr 29 '13 at 16:25
Not at all, go for it. – cdhowie Apr 29 '13 at 16:25
Thanks to all. All of your answers have been very helpful! – Marika Blum Apr 29 '13 at 16:47

score 4 · Answer 2 · answered Apr 29 '13 at 16:23

This is a classic use of itertools.chain.from_iterable

from itertools import chain
print list(chain.from_iterable(x))

Where this example really shines is when you have an iterable with arbitrary length iterables inside it:

[[0],[12,15],[32,24,101],[42]]

score 0 · Answer 3 · answered Apr 29 '13 at 16:23

0

new_x = []
for elem in x:
    new_x.extend(elem)

This works for any number of elements per sublist.

answered Apr 29 '13 at 16:23

Rushy Panchal

3 Answers3