Python - How to get the first row of each list?

Question

I need to get each row of a list and make a new list. Let me explain.

I have this:

data = [[204.0, u'stock'], [204.0, u'stock']]

I need to transform in this:

column1 = [204.0, 204.0]
colunm2 = [u'stock', u'stock']

Any clues on how can this be done?

Best Regards,

Solution 1

Use zip():

>>> data = [[204.0, u'stock'], [204.0, u'stock']]
>>> zip(*data)
[(204.0, 204.0), (u'stock', u'stock')]
>>> column1, column2 = zip(*data)
>>> column1
(204.0, 204.0)
>>> column2
(u'stock', u'stock')

Or, izip() from itertools:

>>> from itertools import izip
>>> column1, column2 = izip(*data)
>>> column1
(204.0, 204.0)
>>> column2
(u'stock', u'stock')

Solution 2

A simple list comprehension will do the trick.

data = [[204.0, u'stock'], [204.0, u'stock']]

column1 = [i[0] for i in data]
column2 = [i[1] for i in data]

>>> column1
 [204.0, 204.0]
>>> column2
 ['stock', 'stock']