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Python Programs - String

Remove duplicate characters from a string - Python Program

Example 1 :

Python 
text = "programming"
result = "".join(sorted(set(text), key=text.index))
print(result)

Output

 
OUTPUT  :
progamin

Example 2 :

Python 
def remove_duplicate_characters(input_string):
    """
    Removes duplicate characters from a string while preserving
    the order of the first occurrence of each character.

    Args:
        input_string (str): The string from which to remove duplicates.

    Returns:
        str: The string with duplicate characters removed.
    """
    seen_characters = set()
    result_string = []

    for char in input_string:
        if char not in seen_characters:
            result_string.append(char)
            seen_characters.add(char)

    return "".join(result_string)

# Example Usage and Output
string1 = "programming"
output1 = remove_duplicate_characters(string1)
print(f"Original string: '{string1}'")
print(f"String after removing duplicates: '{output1}'")

string2 = "hello world"
output2 = remove_duplicate_characters(string2)
print(f"Original string: '{string2}'")
print(f"String after removing duplicates: '{output2}'")

string3 = "aabbccddeeff"
output3 = remove_duplicate_characters(string3)
print(f"Original string: '{string3}'")
print(f"String after removing duplicates: '{output3}'")

Output

 
OUTPUT  :
Original string: 'programming'
String after removing duplicates: 'progamin'
Original string: 'hello world'
String after removing duplicates: 'helo wrd'
Original string: 'aabbccddeeff'
String after removing duplicates: 'abcdef'

Explanation:

remove_duplicate_characters(input_string) Function:

  • This function takes a single argument, input_string, which is the string to be processed.
  • It initializes an empty set called seen_characters. A set is used because it efficiently stores unique elements and allows for quick lookups (char not in seen_characters).
  • It initializes an empty list called result_string. This list will store the characters in their unique and ordered sequence.
  • The program iterates through each charin the input_string.
  • Inside the loop, it checks if the current charis already present in seen_characters.

If the char is not in seen_characters, it means this is the first occurrence of that character. The character is then appended to result_string, and added to seen_characters to mark it as seen.

  • Finally, "".join(result_string)concatenates the characters in the result_string list back into a single string and returns it.

 

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