Python: Check if the elements of a given list are unique or not

Last update on April 19 2025 12:58:51 (UTC/GMT +8 hours)

Check for Unique Elements in List

Write a Python program to check if the elements of a given list are unique or not.

Visual Presentation:

Sample Solution-1:

Python Code:

# Define a function 'all_unique' that checks if all elements in a list are unique
def all_unique(test_list):
    # Check if the length of the list is greater than the length of the set of the list
    if len(test_list) > len(set(test_list)):
        return False
    return True

# Create a list 'nums1' with duplicate elements
nums1 = [1, 2, 4, 6, 8, 2, 1, 4, 10, 12, 14, 12, 16, 17]
# Print a message indicating the original list
print("Original list:")
# Print the contents of 'nums1'
print(nums1)

# Print a message indicating the check for unique elements in the list
print("\nIs the said list contains all unique elements!")
# Call the 'all_unique' function with 'nums1' and print the result
print(all_unique(nums1)) 

# Create a list 'nums2' with unique elements
nums2 = [2, 4, 6, 8, 10, 12, 14]
# Print a message indicating the original list
print("\nOriginal list:")
# Print the contents of 'nums2'
print(nums2)

# Print a message indicating the check for unique elements in the list
print("\nIs the said list contains all unique elements!")
# Call the 'all_unique' function with 'nums2' and print the result
print(all_unique(nums2))

Sample Output:

Original list:
[1, 2, 4, 6, 8, 2, 1, 4, 10, 12, 14, 12, 16, 17]

Is the said list contains all unique elements!
False

Original list:
[2, 4, 6, 8, 10, 12, 14]

Is the said list contains all unique elements!
True

Flowchart:

Sample Solution-2:

• Use set() on the given list to keep only unique occurrences.
• Use len() to compare the length of the unique values to the original list.

Python Code:

# Define a function 'all_unique' that checks if all elements in a list are unique
def all_unique(test_list):
    # Check if the length of the list is equal to the length of the set of the list
    return len(test_list) == len(set(test_list))

# Create a list 'nums1' with duplicate elements
nums1 = [1, 2, 4, 6, 8, 2, 1, 4, 10, 12, 14, 12, 16, 17]
# Print a message indicating the original list
print("Original list:")
# Print the contents of 'nums1'
print(nums1)

# Print a message indicating the check for unique elements in the list
print("\nIs the said list contains all unique elements!")
# Call the 'all_unique' function with 'nums1' and print the result
print(all_unique(nums1)) 

# Create a list 'nums2' with unique elements
nums2 = [2, 4, 6, 8, 10, 12, 14]
# Print a message indicating the original list
print("\nOriginal list:")
# Print the contents of 'nums2'
print(nums2)

# Print a message indicating the check for unique elements in the list
print("\nIs the said list contains all unique elements!")
# Call the 'all_unique' function with 'nums2' and print the result
print(all_unique(nums2)) 

Sample Output:

Original list:
[1, 2, 4, 6, 8, 2, 1, 4, 10, 12, 14, 12, 16, 17]

Is the said list contains all unique elements!
False

Original list:
[2, 4, 6, 8, 10, 12, 14]

Is the said list contains all unique elements!
True

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to count distinct elements in a list.
• Write a Python program to find duplicate elements in a list.
• Write a Python program to remove duplicate elements while preserving order.
• Write a Python program to check if a list contains only unique characters.

Go to:

• Python Data Type List Exercises Home ↩
• Python Exercises Home ↩

Previous: Write a Python program to extract the nth element from a given list of tuples.
Next: Write a Python program to sort a list of lists by a given index of the inner list.

Python Code Editor: