Remove Duplicate Characters from String in Python

This article will discuss different ways to remove duplicate characters from a string in Python.

Table Of Contents

Supose we have a string,

"Wakanda-Warrior"

We want to delete the duplicate characters from this string and keep the strings in order. The final string should be like,

"Waknd-rio"

There are different ways to do this. Let’s discuss them one by one.

Remove Duplicate Characters from String using set() and sorted()

Pass the string to the set() function. It will return a set of characters containing only unique characters from the given string. Then sort this set by using the str.index() function as the comparator. It will sort the unique characters in a string based on the index positions of characters in the original string. Then join back the sorted unique characters and assign that to the original string variable. This way, you can remove duplicate characters from the string and keep the order as in the original string.

For Example,

strValue = "Wakanda-Warrior"

# Remove duplicate characters from string and keep the order
strValue = ''.join(sorted(set(strValue), key=strValue.index))

print(strValue)

Output

Waknd-rio

It deleted all the duplicate characters from the string.

Remove Duplicate Characters from String using OrderedDict

Create an OrderedDict dictionary with characters in a string as keys. It will keep unique characters in the dictionary as keys, and will not change the order of unique characters. Then join back the unique characters (OrderedDict Keys) and assign that to the original string variable. This way, we can remove duplicate characters from the string and will also keep the order as in the original string.

For Example,

from collections import OrderedDict

strValue = "Wakanda-Warrior"

# Remove duplicate characters from string and keep the order
strValue = ''.join(OrderedDict.fromkeys(strValue)) 

print(strValue)

Output

Waknd-rio

It deleted all the duplicate characters from the string.

Remove Duplicate Characters from String using dict

From Python 3.6 onwards, the dict objects maintain the insertion order by default.

Create a dict object with characters in a string as keys. Then join back the unique characters (dict Keys) and assign that to the original string variable. This way, we can remove duplicate characters from the string and keep the order as in the original string. It will keep only unique characters in the dictionary as keys, and if you are using python 3.6 or later, it will not change the order of unique characters.

For Example,

strValue = "Wakanda-Warrior"

# Remove duplicate characters from string
strValue = ''.join(dict.fromkeys(strValue)) 

print(strValue)

Output

Waknd-rio

It deleted all the duplicate characters from the string.

Remove Duplicate Characters from String using set

After removing the duplicate characters, if keeping the order of unique characters is not a requirement, we can use this technique.

Pass the string to the set() function. It will return a set of characters containing unique characters from the given string. Then join back these unique characters and assign that to the original string variable. This way, you can remove duplicate characters from the string. But the order of the remaining unique characters will not be the same as in the original string.

For Example,

strValue = "Wakanda-Warrior"

# Remove duplicate characters from string
strValue = ''.join(set(strValue)) 

print(strValue)

Output

iWrnkdoa-

It deleted all the duplicate characters from the string.

Summary

We learned about different ways to delete duplicate characters from a string in Python.