Unpacking a list in Python

Unpacking  of list in Python : 

In Python, there is a feature of the List that assigns the right-hand side values to the left-hand side. In another way, it is called unpacking of a List in Python. In packing, we put values into a new list while in unpacking we extract those values into a single variable. 

Example :

  • ( a, b, c ) = list_name.
Unpacking a list in Python

List : 

list is a data structure in Python that is a mutable, or changeable, ordered sequence of elements. Each element or value that is inside of a list is called an item.

Code #1 :

#Python Program 
#rishikesh 
# Program to understand about 
# packing and unpacking in Python

# this lines PACKS values
# into variable a as list type
a = [‘Hi’999‘Prepsters’]

# this lines UNPACKS values
# of variable a
(wel_w, num, org) = a 

print(wel_w)

print(num)

print(org)

Output : 

Hi
999
Prepsters
  • Sometimes there are n numbers of input in one line, which contains one or more variable at any end and an array of number or string. Here we can use this property (Unpacking a List in Python) which simplifies our work. 
  • Python uses a special syntax to pass optional arguments (*args) for List unpacking. This means that there can be any numbers of arguments in place of (*args). We can use any variable name in place of “*args”. 

Code #2 :

#Python Program 
#rishikesh 
# Program to understand about 
# packing and unpacking in Python
#any number of input let’s say it contains number in array , then array and then maximum value of array 
ax=list(map(int,input().split()))
print(‘The given List: ‘,ax)
#n will be size of array *a will be the array and c will be the maximum of array 

 

#value of at index 0 will be assigned to n and value at last index of ax will be assigned to c and rest will be assigned to a
#type of a will be list
n,*a,c=ax
print(‘The size of array: ‘,n) 
print(‘array: ‘,a)
print(‘Max of the array: ‘,c) 

Output : 

The given List: [4, 5, 4, 2, 7, 7]
The size of array: 4
array: [5, 4, 2, 7]
Max of the array: 7