Python: Remove duplicates from a list of integers, preserving order

Last update on May 28 2022 13:41:18 (UTC/GMT +8 hours)

Python Programming Puzzles: Exercise-54 with Solution

Write a Python program to remove duplicates from a list of integers, preserving order.

Input:
[1, 3, 4, 10, 4, 1, 43]
Output:
[1, 3, 4, 10, 43]

Input:
[10, 11, 13, 23, 11, 25, 23, 76, 99]
Output:
[10, 11, 13, 23, 25, 76, 99]

Pictorial Presentation:

Python: Remove duplicates from a list of integers, preserving order.

Sample Solution-1:

Python Code:

#License: https://bit.ly/3oLErEI

def test(nums):
    return list(dict.fromkeys(nums)) 
nums = [1, 3, 4, 10, 4, 1, 43]
print("Original list of numbers:")
print(nums)
print("Remove duplicates from the said list of integers, preserving order:")
print(test(nums))
nums = [10, 11, 13, 23, 11, 25, 23, 76, 99]
print("\nOriginal list of numbers:")
print(nums)
print("Remove duplicates from the said list of integers, preserving order:")
print(test(nums))

Sample Output:

Original list of numbers:
[1, 3, 4, 10, 4, 1, 43]
Remove duplicates from the said list of integers, preserving order:
[1, 3, 4, 10, 43]

Original list of numbers:
[10, 11, 13, 23, 11, 25, 23, 76, 99]
Remove duplicates from the said list of integers, preserving order:
[10, 11, 13, 23, 25, 76, 99]

Flowchart:

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:

Sample Solution-2:

Python Code:

#License: https://bit.ly/3oLErEI

def test(nums):
    result = []
    for x in nums:
        if x not in result:
            result.append(x)
    return result
              
 
nums = [1, 3, 4, 10, 4, 1, 43]
print("Original list of numbers:")
print(nums)
print("Remove duplicates from the said list of integers, preserving order:")
print(test(nums))
nums = [10, 11, 13, 23, 11, 25, 23, 76, 99]
print("\nOriginal list of numbers:")
print(nums)
print("Remove duplicates from the said list of integers, preserving order:")
print(test(nums))

Sample Output:

Original list of numbers:
[1, 3, 4, 10, 4, 1, 43]
Remove duplicates from the said list of integers, preserving order:
[1, 3, 4, 10, 43]

Original list of numbers:
[10, 11, 13, 23, 11, 25, 23, 76, 99]
Remove duplicates from the said list of integers, preserving order:
[10, 11, 13, 23, 25, 76, 99]

Flowchart:

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:

Python Code Editor :

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Next: Find the numbers that are greater than 10 and have odd first and last digits.

Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

The os and os.path modules.

The __file__ constant

os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")

os.path.dirname(path) (returns "the directory name of pathname path")

os.getcwd() (returns "a string representing the current working directory")

os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m