Dictionaries in Python Last Updated : 12 Jun, 2025 Comments Improve Suggest changes Like Article Like Report Try it on GfG Practice Python dictionary is a data structure that stores the value in key: value pairs. Values in a dictionary can be of any data type and can be duplicated, whereas keys can't be repeated and must be immutable. Example: Here, The data is stored in key:value pairs in dictionaries, which makes it easier to find values. Python d = {1: 'Geeks', 2: 'For', 3: 'Geeks'} print(d) Output{1: 'Geeks', 2: 'For', 3: 'Geeks'} How to Create a DictionaryDictionary can be created by placing a sequence of elements within curly {} braces, separated by a 'comma'. Python d1 = {1: 'Geeks', 2: 'For', 3: 'Geeks'} print(d1) # create dictionary using dict() constructor d2 = dict(a = "Geeks", b = "for", c = "Geeks") print(d2) Output{1: 'Geeks', 2: 'For', 3: 'Geeks'} {'a': 'Geeks', 'b': 'for', 'c': 'Geeks'} Dictionary keys are case sensitive: the same name but different cases of Key will be treated distinctly. Keys must be immutable: This means keys can be strings, numbers or tuples but not lists.Keys must be unique: Duplicate keys are not allowed and any duplicate key will overwrite the previous value.Dictionary internally uses Hashing. Hence, operations like search, insert, delete can be performed in Constant Time. From Python 3.7 Version onward, Python dictionary are Ordered. Accessing Dictionary ItemsWe can access a value from a dictionary by using the key within square brackets or get() method. Python d = { "name": "Prajjwal", 1: "Python", (1, 2): [1,2,4] } # Access using key print(d["name"]) # Access using get() print(d.get("name")) OutputPrajjwal Prajjwal Adding and Updating Dictionary ItemsWe can add new key-value pairs or update existing keys by using assignment. Python d = {1: 'Geeks', 2: 'For', 3: 'Geeks'} # Adding a new key-value pair d["age"] = 22 # Updating an existing value d[1] = "Python dict" print(d) Output{1: 'Python dict', 2: 'For', 3: 'Geeks', 'age': 22} Removing Dictionary ItemsWe can remove items from dictionary using the following methods:del: Removes an item by key.pop(): Removes an item by key and returns its value.clear(): Empties the dictionary.popitem(): Removes and returns the last key-value pair. Python d = {1: 'Geeks', 2: 'For', 3: 'Geeks', 'age':22} # Using del to remove an item del d["age"] print(d) # Using pop() to remove an item and return the value val = d.pop(1) print(val) # Using popitem to removes and returns # the last key-value pair. key, val = d.popitem() print(f"Key: {key}, Value: {val}") # Clear all items from the dictionary d.clear() print(d) Output{1: 'Geeks', 2: 'For', 3: 'Geeks'} Geeks Key: 3, Value: Geeks {} Iterating Through a DictionaryWe can iterate over keys [using keys() method] , values [using values() method] or both [using item() method] with a for loop. Python d = {1: 'Geeks', 2: 'For', 'age':22} # Iterate over keys for key in d: print(key) # Iterate over values for value in d.values(): print(value) # Iterate over key-value pairs for key, value in d.items(): print(f"{key}: {value}") Output1 2 age Geeks For 22 1: Geeks 2: For age: 22 Read in detail: Ways to Iterating Over a DictionaryNested Dictionaries Example of Nested Dictionary: Python d = {1: 'Geeks', 2: 'For', 3: {'A': 'Welcome', 'B': 'To', 'C': 'Geeks'}} print(d) Output{1: 'Geeks', 2: 'For', 3: {'A': 'Welcome', 'B': 'To', 'C': 'Geeks'}} Read in Detail: Python Nested Dictionary Python Dictionary Operation ProgramsDictionary Creation Programs.Dictionary Add/Append Programs.Dictionary Removal Programs.Dictionary Access Programs.Dictionary Conversion Programs.Dictionary Programs involving Lists.Dictionary Programs involving String, Tuple and Set.Python Dictionary ProblemsLength of a DictionaryCheck if a Key ExistsAccess a Value by KeyRemove a Key from a DictionaryRemove keys with substring valuesSum All Numeric Values in a DictionaryFind Keys with Maximum ValueRemove Duplicates from a DictionaryFilter Dictionary by Key PrefixCount Frequency of Elements Using DictionaryCheck if two arrays are equal or notMax distance between two occurrences in array2 Sum - Count Pairs with target sum3 Sum - Count all triplets with target sumCount all pairs with absolute difference equal to kRemove minimum elements such that no common elements exist in two arraysCheck If Array Pair Sums Divisible by kLongest subarray with sum divisible by KLongest Subarray having Majority Elements Greater Than KCount distinct elements in every window of size kRelated Dictionary Articles Dictionary ComprehensionDictionary MethodsPython Dictionary ExercisePython Dictionary Quiz Comment More infoAdvertise with us Next Article How to Create a Dictionary in Python A ayushmaan bansal Follow Improve Article Tags : Python python-dict Practice Tags : pythonpython-dict Similar Reads Dictionaries in Python Python dictionary is a data structure that stores the value in key: value pairs. Values in a dictionary can be of any data type and can be duplicated, whereas keys can't be repeated and must be immutable. Example: Here, The data is stored in key:value pairs in dictionaries, which makes it easier to 5 min read How to Create a Dictionary in Python The task of creating a dictionary in Python involves storing key-value pairs in a structured and efficient manner, enabling quick lookups and modifications. A dictionary is an unordered, mutable data structure where each key must be unique and immutable, while values can be of any data type. For exa 3 min read Python - Add Dictionary Items In Python, dictionaries are a built-in data structure that stores key-value pairs. Adding items to a dictionary is a common operation when you're working with dynamic data or building complex data structures. This article covers various methods for adding items to a dictionary in Python.Adding Items 3 min read Python Add Dictionary Key In Python, dictionaries are unordered collections of key-value pairs. Each item in a dictionary is accessed by its unique key, which allows for efficient storage and retrieval of data. While dictionaries are commonly used with existing keys, adding a new key is an essential operation when working wi 4 min read Python Access Dictionary In Python, dictionaries are powerful and flexible data structures used to store collections of data in key-value pairs. To get or "access" a value stored in a dictionary, we need to know the corresponding key. In this article, we will explore all the ways to access dictionary values, keys, and both 4 min read Python Change Dictionary Item A common task when working with dictionaries is updating or changing the values associated with specific keys. This article will explore various ways to change dictionary items in Python.1. Changing a Dictionary Value Using KeyIn Python, dictionaries allow us to modify the value of an existing key. 3 min read Python Remove Dictionary Item Sometimes, we may need to remove a specific item from a dictionary to update its structure. For example, consider the dictionary d = {'x': 100, 'y': 200, 'z': 300}. If we want to remove the item associated with the key 'y', several methods can help achieve this. Let’s explore these methods.Using pop 2 min read Get length of dictionary in Python Python provides multiple methods to get the length, and we can apply these methods to both simple and nested dictionaries. Let’s explore the various methods.Using Len() FunctionTo calculate the length of a dictionary, we can use Python built-in len() method. It method returns the number of keys in d 3 min read Python - Value length dictionary Sometimes, while working with a Python dictionary, we can have problems in which we need to map the value of the dictionary to its length. This kind of application can come in many domains including web development and day-day programming. Let us discuss certain ways in which this task can be perfor 4 min read Python - Dictionary values String Length Summation Sometimes, while working with Python dictionaries we can have problem in which we need to perform the summation of all the string lengths which as present as dictionary values. This can have application in many domains such as web development and day-day programming. Lets discuss certain ways in whi 4 min read Like