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Python dictionary is versatile and powerful data structures that play a vital role in every Python programmer’s toolkit. They allow you to store and manipulate data in a way that is both efficient and easy to understand. In this article, we will take a deep dive into the world of Python dictionary, exploring its creation, manipulation, and practical applications. Whether you are a beginner or an experienced Python developer looking to master dictionaries, this guide will equip you with the knowledge and skills you need to make the most out of this essential Python data structure.<\/p>\n
A dictionary comes in handy when we have to store or manipulate data and create complex data mappings with its use as a nested data structure with efficient operations. It is helpful in mapping a key to its value that can be accessed in constant time which gives it an edge over the list in terms of searching or retrieving the value for a particular key.<\/p>\n
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\nLets see how to use Python dictionary in detail.<\/p>\n
Dictionaries can be created in Python using several ways with the most often used being opening and closing curly braces. We can store values in the dictionary upon its creation where the key and value are separated using a colon (\u2018:\u2019) with the values being separated by a comma (\u2018,\u2019). An example can be detailed as:-<\/p>\n
languages = {\n \"key1\": value1, \n \"key2\": ,value2\n \"key3\": value3,\n \"key4\": value4\n }<\/code><\/pre>\nAnother valid way to create a dictionary is by using the dict() method where the built-in constructor creates a dictionary upon interpreting it.<\/p>\n
Syntax 2 for creating a python dictionary:<\/h3>\ndict = dict(key1='value1', key2='value2')<\/code><\/pre>\nDictionary Comprehension is another but slightly complex way to create a dictionary where an iterator is performed inside to store the key-value pairs in a similar technique to how it is implemented with List Comprehension.<\/p>\n
Syntax 3 for creating a python dictionary:<\/h3>\ndict = {key: value for key, value in (('key1', 'value1'), ('key2', 'value2'))}<\/code><\/pre>\nNow that we have a clear idea on how to create a dictionary, we will move forward to study how manipulations can be made on a Python Dictionary.<\/p>\n
Accessing a Python Dictionary<\/h2>\n
Dictionaries in Python can be accessed such that we must provide a key to access the value such as in the given example, a Python Dictionary named languages will have a key named Python, whose value will be printed. In case, the key is not present in dictionary then an error will be thrown:- <\/p>\n
Syntax for accessing single value with the given key of python dictionary:<\/h3>\nprint(languages[\"Python\"])\n\nprint(languages.get(\"Python\"))<\/code><\/pre>\nIn case, we want to access all the elements of the dictionary, inclusive of key and value, then the item() method can be called to access the elements. A for loop can be handy in doing so as given given below:-<\/p>\n
Syntax for accessing key value pair of python dictionary:<\/h3>\nfor key, value in languages.items():\n print(f\"{key} was created in {value}\")<\/code><\/pre>\nManipulating Dictionary in Python<\/h2>\n
Having studied how to create and read a dictionary in python, let’s move onto the techniques we resort to while updating and deleting the keys lying inside the dictionary. To insert a key, we can either place the key inside square brackets with the name of the dictionary and assign the value to it.<\/p>\n
Syntax for manipulating the value of given key:<\/h3>\nlanguages[key] = value<\/code><\/pre>\nAlso, we can use the update function to insert a keys with its subsequent values, that can be mentioned as follow:-<\/p>\n
languages.update({\"Python\": 1})<\/code><\/pre>\nAs far as deleting a key from the dictionary is concerned, the operation can be performed with the del or pop method.<\/p>\n
Syntax for deleting a key value pair:<\/h3>\nlanguages.pop(\"Python\")\ndel languages[\"Python\"]<\/code><\/pre>\nTypes of Dictionaries in Python<\/h2>\n
The power of dictionaries is not limited to these as there are fancy dictionaries that can be imported for their various required use cases. Collection library has various dictionaries like Counter and defaultdict that are used as a tool for problem-solving.<\/p>\n
1. Defaultdict<\/h3>\n
It is a subclass of the general python dictionary and it has a default value for a key in case the key is not found in the dictionary. On creating a defaultdict, we pass the default value, whether we need it to be 0 (int) or an empty list (list). Here is an example with output printed in.<\/p>\n
Code for Defaultdict:<\/strong><\/p>\n\t\t\t\t\t\t