Python | Unpacking tuple of lists

Difficulty Level : Basic
Last Updated : 04 Apr, 2019

Given a tuple of lists, write a Python program to unpack the elements of the lists that are packed inside the given tuple.

Examples:

Input : (['a', 'apple'], ['b', 'ball'])
Output : ['a', 'apple', 'b', 'ball']

Input : ([1, 'sam', 75], [2, 'bob', 39], [3, 'Kate', 87])
Output : [1, 'sam', 75, 2, 'bob', 39, 3, 'Kate', 87]

Approach #1 : Using reduce()

reduce() is a classic list operation used to apply a particular function passed in its argument to all of the list elements. In this case we used add function of operator module which simply adds the given list arguments to an empty list.

# Python3 program to unpack 
# tuple of lists
from functools import reduce
import operator
  
def unpackTuple(tup):
      
    return (reduce(operator.add, tup))
  
# Driver code
tup = (['a', 'apple'], ['b', 'ball'])
print(unpackTuple(tup))

Output:

['a', 'apple', 'b', 'ball']

Approach #2 : Using Numpy [Alternative to Approach #1]

# Python3 program to unpack 
# tuple of lists
from functools import reduce
import numpy
   
def unpackTuple(tup):
       
    print (reduce(numpy.append, tup))
      
# Driver code
tup = (['a', 'apple'], ['b', 'ball'])
unpackTuple(tup)

Output:

['a' 'apple' 'b' 'ball']

Approach #3 : Using itertools.chain(*iterables)

itertools.chain(*iterables) make an iterator that returns elements from the first iterable until it is exhausted, then proceeds to the next iterable, until all of the iterables are exhausted. This makes our job a lot easier, as we can simply append each iterable to the empty list and return it.

# Python3 program to unpack 
# tuple of lists
from itertools import chain
  
def unpackTuple(tup):
    res = []
    for i in chain(*tup):
        res.append(i)
          
    print(res)
      
# Driver code
tup = (['a', 'apple'], ['b', 'ball'])
unpackTuple(tup)

Output:

['a', 'apple', 'b', 'ball']

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Python | Unpacking tuple of lists