Presenting today is a tutorial covering some of the best Python dictionary examples. We believe it is a valuable resource for anyone who wants to learn more about this important data structure.
The tutorial provides a clear and concise overview of Python dictionaries, including their key features and common uses. It also includes a variety of examples, which are well-explained and easy to follow.
Must Read: What is a Python Dictionary with Example?
Practice with the Best Python Dictionary Examples
Before we start, look at some specific benefits that you can gain from the tutorial:
- Learn what Python dictionaries are and how to use them.
- Understand the different types of Python dictionaries and their purposes.
- Learn how to create, access, and modify Python dictionaries.
- Learn how to use Python dictionaries to solve a variety of problems.
First of all, the following is an important question that you must clearly understand.
Check This: Python Code to Convert a Dict to JSON
What is a Python dictionary?
Python dictionaries store key-value pairs, which are data structures that map keys to values. Additionally, dictionaries can store any immutable object as a key, such as strings, numbers, or tuples. They can also store any Python object as a value, such as strings, numbers, lists, or dictionaries.
Unordered dictionaries do not guarantee the order in which the key-value pairs are stored. Additionally, dictionaries are mutable, meaning that the values in a dictionary can change after it is created.
There are two ways to create a Python dictionary:
- Using curly braces (
{})
my_dict = {}- Using the
dict()function:
my_dict = dict()To add key-value pairs to a dictionary, you can use the following syntax:
my_dict["key"] = "value"Also Check: Python Code to Convert a Dict to DataFrame
Best Python Dictionary Examples
Let’s explore various examples of Python dictionaries categorized by common use cases to help you grasp the concept easily.
Moreover, these are potential Python interview problems with their code that the interviewer can ask to solve using dicts only:
Problem#1
Write a function that takes a dict as input and returns a list of all the unique values in the dict .
Python code:
def get_unique_values(dict1):
"""Returns a list of all the unique values in the given dictionary.
Args:
dict1: A dictionary.
Returns:
A list of all the unique values in dict1.
"""
unique_values = set()
for value in dict1.values():
unique_values.add(value)
return list(unique_values)
# Example usage:
dict1 = {"apple": "a fruit", "banana": "another fruit", "orange": "another fruit"}
unique_values = get_unique_values(dict1)
print(unique_values)
Output:
['a fruit', 'another fruit']
Check This: Python Code to Add Elements to a Dict
Problem#2
Write a function that takes two dicts as input and merges them into a single dict , overwriting any duplicate keys.
Python code:
def merge_dicts(dict1, dict2):
"""Merges two dictionaries into a single dictionary, overwriting any duplicate keys.
Args:
dict1: A dictionary.
dict2: A dictionary.
Returns:
A new dictionary with the merged contents of dict1 and dict2.
"""
merged_dict = dict1.copy()
merged_dict.update(dict2)
return merged_dict
# Example usage:
dict1 = {"apple": "a fruit", "banana": "another fruit"}
dict2 = {"orange": "another fruit", "pear": "another fruit"}
merged_dict = merge_dicts(dict1, dict2)
print(merged_dict)
Output:
{'apple': 'a fruit', 'banana': 'another fruit', 'orange': 'another fruit', 'pear': 'another fruit'}
Try This Now: Search a dictionary by key in Python example
Problem#3
Write a function that takes a dict as input and returns a dict with the keys and values reversed.
Python code:
def reverse_dict(dict1):
"""Reverses the keys and values of a dictionary.
Args:
dict1: A dictionary.
Returns:
A new dictionary with the keys and values reversed.
"""
reversed_dict = {}
for key, value in dict1.items():
reversed_dict[value] = key
return reversed_dict
# Example usage:
dict1 = {"apple": "a fruit", "banana": "another fruit"}
reversed_dict = reverse_dict(dict1)
print(reversed_dict)
Output:
{'a fruit': 'apple', 'another fruit': 'banana'}
We hope the above examples are helpful!
Here are some more Python dict examples with their solutions that the interviewer can ask to solve using dictionaries only:
Problem#4
Write a function that takes a list of strings as input and returns a dict with each string as a key and its count as the value.
Python code:
def count_strings(str_list):
"""Returns a dictionary with each string in str_list as a key and its count as the value.
Args:
str_list: A list of strings.
Returns:
A dictionary with each string in str_list as a key and its count as the value.
"""
str_counts = {}
for str in str_list:
if str in str_counts:
str_counts[str] += 1
else:
str_counts[str] = 1
return str_counts
# Example usage:
str_list = ["apple", "banana", "apple", "orange", "apple"]
str_counts = count_strings(str_list)
print(str_counts)
Output:
{'apple': 3, 'banana': 1, 'orange': 1}
Problem#5
Write a function that takes a dict as input and returns a list of all the keys that have a value greater than a certain threshold.
Python code:
def get_keys_with_value_greater_than_threshold(dict1, threshold):
"""Returns a list of all the keys in dict1 that have a value greater than threshold.
Args:
dict1: A dictionary.
threshold: A value.
Returns:
A list of all the keys in dict1 that have a value greater than threshold.
"""
keys_with_greater_value = []
for key, value in dict1.items():
if value > threshold:
keys_with_greater_value.append(key)
return keys_with_greater_value
# Example usage:
dict1 = {"apple": 10, "banana": 5, "orange": 20}
threshold = 10
keys_with_greater_value = get_keys_with_value_greater_than_threshold(dict1, threshold)
print(keys_with_greater_value)
Output:
['apple', 'orange']
Also Read: Python Ordered Dictionary By Key
Problem#6
Write a function that takes an OrderedDict as input and returns a list of all the keys in the OrderedDict in the order that they were inserted.
Python code:
def get_keys(or_dict):
"""Returns a list of all the keys in the given OrderedDict in the order that they were inserted.
Args:
or_dict: An OrderedDict.
Returns:
A list of all the keys in or_dict in the order that they were inserted.
"""
keys_in_order = []
for key, value in or_dict.items():
keys_in_order.append(key)
return keys_in_order
# Example usage:
or_dict = OrderedDict([("apple", "a fruit"), ("banana", "another fruit"), ("orange", "another fruit")])
keys_in_order = get_keys(or_dict)
print(keys_in_order)
We hope these problems are helpful!
Python dicts are versatile and can be applied to various scenarios. They provide a convenient way to store and manipulate data in a key-value format. With these examples, you should be well on your way to using dictionaries effectively in your Python programs.
Conclusion
In conclusion, we hope this article has been helpful. I have provided solutions to five common Python interview problems using dictionaries only. These problems are all relatively short, but they cover a variety of important concepts, such as getting unique values, merging dictionaries, reversing dictionaries, counting strings, and getting keys with values greater than a certain threshold. We encourage you to practice solving these problems on your own to solidify your understanding of dictionaries and Python programming in general.
