CODEWITHSUNDEEP
pythonpython-2.7
bhansa
bhansa

Reputation: 7504

How do I make two different lists with the corresponding elements of the first list?

Suppose I have a list like this:

[[1, 2], [2, 3], [5, 4]]

What I want is two different lists from the above list with first element in one list and
the second element in the other.

The result will look like this:

[1,2,5] and [2,3,4]

Is there any way to do it by using list splicing ?

Upvotes: 1

Views: 44

Answers (2)

Martijn Pieters
Martijn Pieters

Reputation: 1121494

Use zip() to pair up the elements of the input lists:

lista, listb = zip(*inputlist)

The * applies the elements in inputlist as separate arguments, as if you called zip() as zip([1, 2], [2, 3], [5, 4]). zip() takes the first element of each argument and returns those together, and then the second element, etc.

This produces tuples, not lists, really, but that's easy to remedy:

lista, listb = map(list, zip(*inputlist))

Demo:

>>> inputlist = [[1, 2], [2, 3], [5, 4]]
>>> zip(*inputlist)
[(1, 2, 5), (2, 3, 4)]
>>> lista, listb = map(list, zip(*inputlist))
>>> lista
[1, 2, 5]
>>> listb
[2, 3, 4]

Upvotes: 2

akuiper
akuiper

Reputation: 214927

How about use numpy array?

import numpy as np
np.array(myList).transpose()

# array([[1, 2, 5],
#        [2, 3, 4]])

Or 

np.array(myList)[:, 0]
# array([1, 2, 5])

np.array(myList)[:, 1]
# array([2, 3, 4])

Upvotes: 1

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