Separate lists stored in a variable using Python

Question

How can I transform

list = [[68.0], [79.0], [6.0]],  ... [[176.0], [120.0], [182.0]]

into

result = [68.0, 79.0, 6.0, 8.0], ... [176.0, 120.0, 182.0]

for example, I need individual lists from variable 'list' like this: list1 = [68.0, 79.0, 6.0, 8.0, 61.0, 88.0, 59.0, 91.0] — Ibe
– Ibe, Commented May 21, 2013 at 15:03
@towi, I would like to point out that original question was not only about to flatten out sublists but also to map them as well so that individual lists can be indexed out as required. — Ibe
– Ibe, Commented May 22, 2013 at 14:02
@Ibe Oh? I could not see that from your original formulation. I am sorry -- but feel free to correct my correction. I can not see what you are driving at. — towi
– towi, Commented May 28, 2013 at 20:01

Jon Clements · Accepted Answer · 2013-05-21 15:09:32Z

1

If I've correctly understood what input_lists should actually look like, then I think what you're after is creating a dict so that dict[n] is your nth list. eg: the following code:

input_lists = [[[68.0], [79.0], [6.0], [8.0], [61.0], [88.0], [59.0], [91.0]],
       [[10.0], [11.0], [9.0], [120.0], [92.0], [12.0], [8.0], [13.0]],
       [[17.0], [18.0], [13.0], [14.0], [12.0], [176.0], [120.0], [182.0]]]


lists = {i:[el[0] for el in v] for i, v in enumerate(input_lists, start=1)}
# {1: [68.0, 79.0, 6.0, 8.0, 61.0, 88.0, 59.0, 91.0], 2: [10.0, 11.0, 9.0, 120.0, 92.0, 12.0, 8.0, 13.0], 3: [17.0, 18.0, 13.0, 14.0, 12.0, 176.0, 120.0, 182.0]}

answered May 21, 2013 at 15:09

Jon Clements

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2 Comments

Ibe Over a year ago

It gave error: TypeError: 'float' object is not subscriptable. sublists are not separated by commas and no outer brackets.

Ibe Over a year ago

I first append the variable to a list within a for loop and then used your lists argument outside loop to separate lists. It worked. Thanks.

Divanshu · Accepted Answer · 2013-05-21 15:06:43Z

1

z = []
for x in list:
    for i in x:
        z.append(i)

answered May 21, 2013 at 15:06

Divanshu

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2 Comments

glglgl Over a year ago

z = [i for x in list for i in x] would be simper and more concise for that.

Divanshu Over a year ago

I wrote this answer taking in consideration that person who asked the question might be a beginner. This would be easy to read for him.

Srikar Appalaraju · Accepted Answer · 2013-05-21 16:24:56Z

1

Am I missing something or a simple list comprehension would do? And also list is a keyword in python PLEASE DO NOT name your variables which create conflict with python keywords. It will bite you in places you cant imagine.

>>> mylist = [[68.0], [79.0], [6.0], [8.0], [61.0], [88.0], [59.0], [91.0]]
>>> [i[0] for i in mylist]
[68.0, 79.0, 6.0, 8.0, 61.0, 88.0, 59.0, 91.0] #this can be assigned to a new list var mylist1

UPDATE: Based on what lbe said, changing the approach -

>>> mylist =[[[68.0], [79.0], [6.0], [8.0], [61.0], [88.0], [59.0], [91.0]],
...        [[10.0], [11.0], [9.0], [120.0], [92.0], [12.0], [8.0], [13.0]],
...        [[17.0], [18.0], [13.0], [14.0], [12.0], [176.0], [120.0], [182.0]]]
>>> [i[0] for i in reduce(lambda x, y: x+y, mylist)]
[68.0, 79.0, 6.0, 8.0, 61.0, 88.0, 59.0, 91.0, 10.0, 11.0, 9.0, 120.0, 92.0, 12.0, 8.0, 13.0, 17.0, 18.0, 13.0, 14.0, 12.0, 176.0, 120.0, 182.0]

edited May 21, 2013 at 16:24

answered May 21, 2013 at 15:07

Srikar Appalaraju

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2 Comments

Ibe Over a year ago

The only problem is that this list is part of a for loop so if I try your suggestion then mylist[0] returns: 68.0 10.0 17.0 not a horizontal list as I provided above .

njzk2 Over a year ago

@lbe: so you simply replace mylist by mylist[0] in the above code

Henry Schreiner · Accepted Answer · 2013-05-21 15:11:14Z

First, the code above is invalid syntax. You need surrounding brackets or something similar.

Possibility one:

list =[[[68.0], [79.0], [6.0], [8.0], [61.0], [88.0], [59.0], [91.0]],
       [[10.0], [11.0], [9.0], [120.0], [92.0], [12.0], [8.0], [13.0]],
       [[17.0], [18.0], [13.0], [14.0], [12.0], [176.0], [120.0], [182.0]]]

Then list[0], list[1], etc. refer to the sub-lists.

Possibility two:

list =[[68.0], [79.0], [6.0], [8.0], [61.0], [88.0], [59.0], [91.0],
       [10.0], [11.0], [9.0], [120.0], [92.0], [12.0], [8.0], [13.0],
       [17.0], [18.0], [13.0], [14.0], [12.0], [176.0], [120.0], [182.0]]

That is, you want chunks of a long list. Then, just use slice syntax, ie, list[0:2] would be [[68.0], [79.0], [6.0]].

Matthew Plourde · Accepted Answer · 2013-05-21 15:16:36Z

0

Assuming your data looks like it does in @JonClements answer, here's another approach using list comprehension.

[reduce(lambda x, y: x + y, l) for l in input_lists]
# [[68.0, 79.0, 6.0, 8.0, 61.0, 88.0, 59.0, 91.0],
#  [10.0, 11.0, 9.0, 120.0, 92.0, 12.0, 8.0, 13.0],
#  [17.0, 18.0, 13.0, 14.0, 12.0, 176.0, 120.0, 182.0]]

answered May 21, 2013 at 15:16

Matthew Plourde

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1 Comment

Ibe Over a year ago

The only problem is that this list is part of a for loop so if I try your suggestion then input_lists[0] returns (not a horizontal list as I provided above): 68.0 10.0 17.0

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