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Remove all duplicates from a given string in Python
  • Difficulty Level : Easy
  • Last Updated : 22 Nov, 2020

We are given a string and we need to remove all duplicates from it? What will be the output if the order of character matters?

Input : geeksforgeeks
Output : efgkos

This problem has existing solution please refer Remove all duplicates from a given string.
Method 1:

from collections import OrderedDict 
# Function to remove all duplicates from string 
# and order does not matter 
def removeDupWithoutOrder(str): 
    # set() --> A Set is an unordered collection 
    #         data type that is iterable, mutable, 
    #         and has no duplicate elements. 
    # "".join() --> It joins two adjacent elements in 
    #             iterable with any symbol defined in 
    #             "" ( double quotes ) and returns a 
    #             single string 
    return "".join(set(str)) 
# Function to remove all duplicates from string 
# and keep the order of characters same 
def removeDupWithOrder(str): 
    return "".join(OrderedDict.fromkeys(str)) 
# Driver program 
if __name__ == "__main__"
    str = "geeksforgeeks"
    print ("Without Order = ",removeDupWithoutOrder(str)) 
    print ("With Order = ",removeDupWithOrder(str)) 


Without Order =  egfkosr
With Order    =  geksfor

Method 2:

def removeDuplicate(str):
    print("Without Order:",s)
    for i in str:
        if(i in t):
        print("With Order:",t)


Without Order: rofgeks
With Order: geksfor

What do OrderedDict and fromkeys() do ?

An OrderedDict is a dictionary that remembers the order of the keys that were inserted first. If a new entry overwrites an existing entry, the original insertion position is left unchanged.

For example see below code snippet :

from collections import OrderedDict
ordinary_dictionary = {}
ordinary_dictionary['a'] = 1
ordinary_dictionary['b'] = 2
ordinary_dictionary['c'] = 3
ordinary_dictionary['d'] = 4
ordinary_dictionary['e'] = 5
# Output = {'a': 1, 'c': 3, 'b': 2, 'e': 5, 'd': 4}
print (ordinary_dictionary)    
ordered_dictionary = OrderedDict()
ordered_dictionary['a'] = 1
ordered_dictionary['b'] = 2
ordered_dictionary['c'] = 3
ordered_dictionary['d'] = 4
ordered_dictionary['e'] = 5
# Output = {'a':1,'b':2,'c':3,'d':4,'e':5}
print (ordered_dictionary)      

fromkeys() creates a new dictionary with keys from seq and values set to value and returns list of keys, fromkeys(seq[, value]) is the syntax for fromkeys() method.

Parameters :

  • seq : This is the list of values which would be used for dictionary keys preparation.
  • value : This is optional, if provided then value would be set to this value.

For example see below code snippet :

from collections import OrderedDict
seq = ('name', 'age', 'gender')
dict = OrderedDict.fromkeys(seq)
# Output = {'age': None, 'name': None, 'gender': None}
print (str(dict)) 
dict = OrderedDict.fromkeys(seq, 10)
# Output = {'age': 10, 'name': 10, 'gender': 10}
print (str(dict))       

This article is contributed by Shashank Mishra (Gullu). If you like GeeksforGeeks and would like to contribute, you can also write an article using or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

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