Nested list manipulation, double forloop needed?

Question

So I want to change this nested(list) lets call it X

[['What if?', ' 2014', ' Randall Munroe'], ['Thing Explainer', ' 2015', ' Randall Munroe'], ['Alan Turing: The Enigma', ' 2014', ' Andrew Hodges']]

To This nested(list) lets it Y

[['What if', 'Thing Explainer', 'Alan Turing: The Enigma'], [ 2014,2015,2014], ['Randall Munroe, Randall Munroe, 'Andrew Hodges']]

The first term in Y is the first item in the ith term in X.

['What if', 'Thing Explainer', 'Alan Turing: The Enigma']

The second term in Y is the second item in the ith term in X

['Randall Munroe, Randall Munroe, 'Andrew Hodges']

Can anyone share there thought process and solutions in python?

Colin Schoen · Answer 1 · 2015-12-01T04:45:00.940

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You will want to use the built-in zip function in Python.

>>> zip(*[['What if?', ' 2014', ' Randall Munroe'], ['Thing Explainer', ' 2015', ' Randall Munroe'], ['Alan Turing: The Enigma', ' 2014', ' Andrew Hodges']])

There is more documentation located at https://docs.python.org/3/library/functions.html#zip

edited Dec 01 '15 at 04:45

answered Dec 01 '15 at 04:05

Colin Schoen

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You would need to unpack the arguments to the `zip` function i.e. `zip(*your_list)`. – AKS Dec 01 '15 at 04:44
Yeah, I still want to return a nested loop – Sajeed Bakht Dec 01 '15 at 05:04

score 0 · Answer 2 · answered Dec 01 '15 at 04:07

I'm not sure what packages you want to/don't want to use. But numpy can do this quite easily:

import numpy as np
dat = [['What if?', ' 2014', ' Randall Munroe'], ['Thing Explainer', ' 2015', ' Randall Munroe'], ['Alan Turing: The Enigma', ' 2014', ' Andrew Hodges']]
np.array(dat).T.tolist()
# [['What if?', 'Thing Explainer', 'Alan Turing: The Enigma'],
#  [' 2014', ' 2015', ' 2014'],
#  [' Randall Munroe', ' Randall Munroe', ' Andrew Hodges']]

Sorry can't import anything :S – Sajeed Bakht Dec 01 '15 at 05:03 — Sajeed Bakht, Dec 01 '15 at 05:03

Dharmraj · Accepted Answer · 2015-12-07T08:51:01.947

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map (list, zip(*[['What if?', ' 2014', ' Randall Munroe'], ['Thing Explainer', ' 2015', ' Randall Munroe'], ['Alan Turing: The Enigma', ' 2014', ' Andrew Hodges']]))

This will do you exactly what you need.

edited Dec 07 '15 at 08:51

answered Dec 01 '15 at 09:32

Dharmraj

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But I want a nested listed returned if I do it your way this happens a = map (list, zip(*[['What if?', ' 2014', ' Randall Munroe'], ['Thing Explainer', ' 2015', ' Randall Munroe'], ['Alan Turing: The Enigma', ' 2014', ' Andrew Hodges']])) print(a) – Sajeed Bakht Dec 01 '15 at 16:08
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Just converted it to list object, thank you !!! – Sajeed Bakht Dec 01 '15 at 16:24

Nested list manipulation, double forloop needed?

3 Answers3