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# Python | Combine the first and last items separately in a list

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Examples :

`  Input:  [[’x’,’ y’], [’a’,’ b’], [ ’m’,’ n’]]  Output:  [[’x’,’ a’, ’m’], [’ y’, ’b’,’ n’]]  Input:  [[1, 2], [3, 4], [5, 6], [7, 8]]  Output:  [[1, 3, 5, 7] , [2, 4, 6, 8]] `

Approach # 1: list comprehension and `zip`

 ` # Python3 program for merging the first and the last ` ` # elements separately in the list of lists `   ` def ` ` merge (lst): `   ` return ` ` [` ` list ` ` (ele) ` ` for ` ele ` in ` ` list ` ` (` ` zip ` ` (` ` * ` ` lst) )] `   ` # Driver code ` ` lst ` ` = ` ` [[` ` ’x’ ` `, ` `’ y’ ` `], [` ` ’a’ ` `, ` `’ b’ ` `], [` ` ’m’ ` `, ` `’ n’ ` `]] ` ` print ` ` (merge (lst)) `

Exit:

` [[’x ’,’ a’, ’m’], [’ y’, ’b’,’ n’]] `
Approach # 2 Using the Numpy

array

First convert the given list to a numpy array and then return the transpose of the array and finally convert the array to a list.

 ` # Python3 program to merge first and last ` ` # elements separately in the list of lists ` ` import ` ` numpy as np `   ` def ` ` merge (lst): ` ` arr ` ` = ` ` np.array (lst) ` ` return ` ` arr.T.tolist () `   ` # Driver code ` ` lst ` ` = ` ` [[` ` ’x’ ` `, ` ` ’y’ ` `], [` `’ a’ ` `, ` ` ’b’ ` `], [` `’ m’ ` `, ` ` ’n’ ` `]] ` ` print ` ` (merge (lst)) `

Exit:

` [[’x’,’ a’, ’m’], [’ y’, ’b’,’ n ’]] `

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