Print first n distinct permutations of string using itertools in Python

Last Updated : 07 Jan, 2019

Given a string with duplicate characters allowed, print first n permutations of given string such that no permutation is repeated.

Examples:

  Input : string = "abcab", n = 10  Output : aabbc aabcb aacbb ababc abacb                  abbac abbca abcab abcba acabb    Input : string = "okok", n = 4  Output : kkoo koko kook okko

Approach:
Python provides an inbuilt method to find the permutations of any given sequence which is present in the itertools package. But this method doesn’t provide unique permutations. Hence to ensure that any permutation is not repeated, we use a set and follow the below conditions:

If the permutation is not present in the set, print it and insert it in the set. Increment the count of number of unique permutations.
Else, move on to the next permutation.

Below is the implementation of the above approach:

   # Python3 program to print first n unique  
# permutations of the string using itertools 
from itertools import permutations 
  
# Function to print first n unique  
# permutation using itertools  
def nPermute(string, n):  
  
    # Convert the string to list and sort  
    # the characters in alphabetical order 
    strList = sorted(list(string)) 
      
    # Create an iterator 
    permList = permutations(strList) 
  
    # Keep iterating until we  
    # reach nth unique permutation 
    i = 0
    permSet = set() 
    tempStr = ''  
      
    while i < n: 
        tempStr = ''.join(permList.__next__()) 
          
        # Insert the string in the set 
        # if it is not already included 
        # and print it out. 
        if tempStr not in permSet: 
            permSet.add(tempStr) 
            print(tempStr) 
            i += 1
      
# Driver code  
if __name__ == "__main__": 
  
    string = "ababc"
    n = 10
    nPermute(string, n)  
 
  

Output:

  aabbc  aabcb  aacbb  ababc  abacb  abbac  abbca  abcab  abcba  acabb

Python | Permutation of a given string using inbuilt function

rituraj_jain

Improve

Article Tags :

Practice Tags :

The task is to generate all the possible permutations of a given string. A permutation of a string is a rearrangement of its characters. For example, the permutations of "ABC" are "ABC", "ACB", "BAC", "BCA", "CAB", and "CBA". The number of permutations of a string with n unique characters is n! (fac

2 min read

All permutations of a string using iteration

A permutation, also called an â€œarrangement numberâ€ or â€œorderâ€, is a rearrangement of the elements of an ordered list S into a one-to-one correspondence with S itself. A string of length n has n! permutation ( Source: Mathword ) Below are the permutations of string ABC. ABC ACB BAC BCA CBA CAB We hav

4 min read

Print all Unique permutations of a given string.

Given a string that may contain duplicates, the task is find all unique permutations of given string in any order. Examples: Input: "ABC"Output: ["ABC", "ACB", "BAC", "BCA", "CAB", "CBA"]Explanation: Given string ABC has 6 unique permutations as "ABC", "ACB", "BAC", "BCA", "CAB" and "CBA". Input: "A

12 min read

Permutations of a given string using STL

Given a string s, the task is to return all unique permutations of a given string in lexicographically sorted order. Note: A permutation is the rearrangement of all the elements of a string. Examples: Input: s = "ABC"Output: "ABC", "ACB", "BAC", "BCA", "CBA", "CAB" Input: s = "XY"Output: "XY", "YX"

4 min read

Print all the permutations of a string without repetition using Collections in Java

Given a string str, the task is to print all the permutations of str. A permutation is an arrangement of all or part of a set of objects, with regard to the order of the arrangement. A permutation should not have repeated strings in the output. Examples: Input: str = "aa" Output: aa Note that "aa" w

2 min read

Print all the permutation of length L using the elements of an array | Iterative

Given an array of unique elements, we have to find all the permutations of length L using the elements of the array. Repetition of elements is allowed.Examples: Input: arr = { 1, 2 }, L=3 Output: 111 211 121 221 112 212 122 222Input: arr = { 1, 2, 3 }, L=2 Output: 11 21 31 12 22 32 13 23 33 Approach

5 min read

Distinct permutations of the string | Set 2

6 min read

Distinct permutations of a string containing duplicates using HashSet in Java

Given a string str that may contain duplicate characters, the task is to print all the distinct permutations of the given string such that no permutation is repeated in the output. Examples: Input: str = "ABA" Output: ABA AAB BAA Input: str = "ABC" Output: ABC ACB BAC BCA CBA CAB Approach: An approa

2 min read

Create multiple copies of a string in Python by using multiplication operator

In Python, creating multiple copies of a string can be done in a simple way using multiplication operator. In this article, we will focus on how to achieve this efficiently. Using multiplication operator (*)This method is the easiest way to repeat a string multiple times in Python. It directly gives

1 min read

Find the N-th lexicographic permutation of string using Factoradic method

Given string str with unique characters and a number N, the task is to find the N-th lexicographic permutation of the string using Factoradic method. Examples: Input: str = "abc", N = 3 Output: bac Explanation: All possible permutations in sorted order: abc, acb, bac, bca, cab, cba 3rd permutation i

7 min read

Print first n distinct permutations of string using itertools in Python

Similar Reads