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random.shuffle() function in Python
  • Last Updated : 26 May, 2020

sample() is an inbuilt method of the random module. It is used to shuffle a sequence (list). Shuffling means changing the position of the elements of the sequence. Here, the shuffling operation is inplace.

random.shuffle()

Syntax : random.shuffle(sequence, function)

Parameters :
sequence : can be a list
function : optional and by default is random(). It should return a value between 0 and 1.

Returns : nothing

Example 1 : Shuffling a list






# import the random module
import random
  
  
# declare a list
sample_list = ['A', 'B', 'C', 'D', 'E']
  
print("Original list : ")
print(sample_list)
  
# first shuffle 
random.shuffle(sample_list)
print("\nAfter the first shuffle : ")
print(sample_list)
  
# second shuffle
random.shuffle(sample_list)
print("\nAfter the second shuffle : ")
print(sample_list)

Output :

Original list : 
['A', 'B', 'C', 'D', 'E']

After the first shuffle : 
['A', 'B', 'E', 'C', 'D']

After the second shuffle : 
['C', 'E', 'B', 'D', 'A']

The shuffle() method cannot be used to shuffle immutable datatypes like strings.

Example 2:




# import the random module
import random
  
  
# user defined function to shuffle
def sample_function():
    return 0.5
  
sample_list = ['A', 'B', 'C', 'D', 'E']
print("Original list : ")
print(sample_list)
  
# as sample_function returns the same value
# each time, the order of shuffle will be the
# same each time
random.shuffle(sample_list, sample_function)
print("\nAfter the first shuffle : ")
print(sample_list)
  
sample_list = ['A', 'B', 'C', 'D', 'E']
  
random.shuffle(sample_list, sample_function)
print("\nAfter the second shuffle : ")
print(sample_list)

Output :

Original list : 
['A', 'B', 'C', 'D', 'E']

After the first shuffle : 
['A', 'D', 'B', 'E', 'C']

After the second shuffle : 
['A', 'D', 'B', 'E', 'C']

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