Python: Create a new string with no duplicate consecutive letters from a given string

Last update on May 24 2025 10:48:20 (UTC/GMT +8 hours)

Remove Consecutive Duplicates

Write a Python program to create a string with no duplicate consecutive letters from a given string.

Sample Solution:

Python Code:

# Define a function named no_consecutive_letters that takes a string (txt) as an argument.
def no_consecutive_letters(txt):
    # Return the first character of the string and join the characters where the current character is not equal to the previous character.
    # The expression txt[i] for i in range(1, len(txt)) if txt[i] != txt[i-1] iterates over the characters, excluding consecutive duplicates.
    return txt[0] + ''.join(txt[i] for i in range(1, len(txt)) if txt[i] != txt[i-1])

# Test the function with different strings and print the results.

# Test case 1
print(no_consecutive_letters("PPYYYTTHON"))

# Test case 2
print(no_consecutive_letters("PPyyythonnn"))

# Test case 3
print(no_consecutive_letters("Java"))

# Test case 4
print(no_consecutive_letters("PPPHHHPPP")) 

Sample Output:

PYTHON
Python
Java
PHP

Explanation:

Here is a breakdown of the above Python code:

• Function definition:
• The code defines a function named "no_consecutive_letters()" that takes a string (txt) as an argument.
• Return Statement:
• The function returns the first character of the string concatenated with the characters where the current character is not equal to the previous character.
• Joining characters:
• The "join()" method is used to concatenate characters where consecutive duplicates are excluded.

Pictorial Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to remove consecutive duplicate characters from a string while preserving letter case.
• Write a Python program to compress a string by replacing groups of consecutive duplicate letters with a single instance.
• Write a Python program to iteratively remove consecutive duplicates from a string until no such duplicates remain.
• Write a Python program to remove only consecutive duplicate vowels from a given string.

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