Extending a list in Python (5 different ways)

Extending a list in python can be done is following ways:
1. Using append() function: We can append at the end of the list by using append() function. For appending any single value to the list or appending a list to the list, the syntax stays the same. But we can only append a single value at a time using append() function

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# Python program to extend a list using append()
  
a = [10, 12, 13, 17
  
# appending multiple values
a.append(20)
a.append(22)
print(a)

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Output:

[10, 12, 13, 17, 20, 22]

2. Using ‘+’ operator: We can add values by using the “+” operator. We can use [] to add any number of values to the list. Adding multiple values can be done by using ‘, ‘ values.

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# Python program to extend a list using '+' 
  
a = [10, 12, 13, 17
  
# Appending single value
a = a + [20]
  
# append more then one values
a = a + [30, 40]
print(a)

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Output:

[10, 12, 13, 17, 20, 30, 40]

3. Using slicing: Using slicing in python, single or multiple values can be added to a list.

a[:0] = [x, y, z…]

Here a is the the list in which the values(x, y, z..) are to be added. In this method the values are appended to the front of the list.

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# Python program to extend a list using 'slicing' 
  
# appending multiple value 
a =[10, 12, 13, 17
  
# add 1 number
a[:0] = [30]
  
# add two numbers
a[:0] = [40, 50]
print(a)

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Output:

[40, 50, 30, 10, 12, 13, 17]

4.Using chain(): Using chain() iterator function, we can extend a list by the syntax:

list(chain(a, [x, y, z..]))

Here a is the the list in which the values(x, y, z..) are to be added. In this method the values are appended to the end of the list.

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# python program to extend a list using 
# "chain" iterator functions
from itertools import *
  
a = [10, 20, 30]
  
# extend a list
print(list(chain(a, [40, 50, 60])))

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Output:

[10, 20, 30, 40, 50, 60]

5. Using Extend

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# Python program to extend a list using extend() 
a = [10, 12, 13, 17
  
b = [30, 40]
  
a.extend(b)
  
print(a)

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Output:

[10, 12, 13, 17, 30, 40]


My Personal Notes arrow_drop_up

Striver(underscore)79 at Codechef and codeforces D

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