Python Program to Set from dictionary values

In Python, a dictionary is an implementation of a data structure known as an associative array. A dictionary is made up of key-value pairs, where each key maps to its corresponding value.

In this article, we will learn how to extract unique values from a dictionary and convert them into a set, which automatically removes duplicates.

Example Overview

Let's start with an example to understand what we want to achieve ?

# Input dictionary with duplicate values
input_dict = {'hello': 5, 'tutorialspoint': 10, 'users': 15, 'python': 5}
print("Input dictionary:", input_dict)
print("Dictionary values:", list(input_dict.values()))

# Convert to set (removes duplicates)
result_set = set(input_dict.values())
print("Set from dictionary values:", result_set)

Input dictionary: {'hello': 5, 'tutorialspoint': 10, 'users': 15, 'python': 5}
Dictionary values: [5, 10, 15, 5]
Set from dictionary values: {10, 5, 15}

Notice how the duplicate value 5 appears only once in the final set.

Method 1: Using values() and set() Functions

The most straightforward approach uses the values() method to extract dictionary values and set() to create a set ?

# Input dictionary
input_dict = {'hello': 5, 'tutorialspoint': 10, 'users': 15, 'python': 5}

# Extract values and convert to set
result_set = set(input_dict.values())
print("Set from dictionary values:", result_set)
print("Number of unique values:", len(result_set))

Set from dictionary values: {10, 5, 15}
Number of unique values: 3

Method 2: Using Set Comprehension

Set comprehension provides a concise way to create a set from dictionary values ?

# Input dictionary
input_dict = {'hello': 5, 'tutorialspoint': 10, 'users': 15, 'python': 5}

# Using set comprehension
result_set = {value for value in input_dict.values()}
print("Set from dictionary values:", result_set)

# Alternative: using keys to access values
result_set2 = {input_dict[key] for key in input_dict}
print("Alternative approach:", result_set2)

Set from dictionary values: {10, 5, 15}
Alternative approach: {10, 5, 15}

Method 3: Using Counter() Function

The Counter from collections module counts value frequencies and can help extract unique values ?

from collections import Counter

# Input dictionary
input_dict = {'hello': 5, 'tutorialspoint': 10, 'users': 15, 'python': 5}

# Count frequency of values
value_counts = Counter(input_dict.values())
print("Value frequencies:", value_counts)

# Extract unique values as a set
result_set = set(value_counts.keys())
print("Set from dictionary values:", result_set)

Value frequencies: Counter({5: 2, 10: 1, 15: 1})
Set from dictionary values: {10, 5, 15}

Comparison

Practical Example

Here's a real-world example showing how to extract unique scores from a student database ?

# Student scores dictionary
students = {
    'Alice': 85,
    'Bob': 92,
    'Charlie': 85,
    'Diana': 78,
    'Eve': 92,
    'Frank': 88
}

# Get unique scores
unique_scores = set(students.values())
print("All scores:", list(students.values()))
print("Unique scores:", sorted(unique_scores))
print("Number of different score levels:", len(unique_scores))

All scores: [85, 92, 85, 78, 92, 88]
Unique scores: [78, 85, 88, 92]
Number of different score levels: 4

Conclusion

The most efficient way to create a set from dictionary values is using set(dict.values()). Use set comprehension for readable code with filtering, and Counter() when you also need frequency information.