What is Python Dictionary?

Published by Anshul Verma on

Python Dictionary (Tutorial With Examples) - Trytoprogram

Dictionaries in python is one such concept, which is unique and gives an edge to python over other programming languages. It is a collection like a list or set but has unique features which will be discussed in this blog. So let us start by taking a look at pointers that will be discussed here:

  • What Is  Dictionaries In Python?
  • Why Use A Dictionary In Python?
  • List vs Dictionary
  • How To Implement A Dictionary?
  • Operations In Dictionaries :
    • Accessing An Element
    • Replacing An Element
    • Removing An Element
    • Other Operations
  • Use Case – Nested Dictionary

What Is A Dictionary In Python

It is a collection data type just like a list or a set, but there are certain features that make python dictionary unique. A dictionary in python is not ordered and is changeable as well. We can make changes in a dictionary unlike sets or strings which are immutable in nature. The dictionaries contains key-value pairs like a map that we have in other programming languages. A dictionary has  indexes. Since the value of the keys we declare in a dictionary are always unique, we can use them as indexes to access the elements in a dictionary.

Also, a dictionary does not have any duplicate members. Although the value elements in the key value pairs can contain duplicate values.

Why Use A Dictionary In Python

First of all, it is not like any other object or data type in python programming language. A dictionary has key value pairs resembling a map. It is often used for unordered data with distinct key values.

It is similar to a real life dictionary. We have distinct keys which we can use to fetch the values specified in them. In case of dictionary, even though there are no duplicate members, we can mention duplicate members in the value elements. Now that we know, why we use a dictionary, lets try to understand how it is different from lists in python.

Lists vs Dictionary

Lists Dictionary
 Ordered  Not ordered
 Access elements use index values  Access elements use keys as index values
 Collection of elements  Collection of key value pairs
 Allows duplicate members  No duplicate members
 Preferred for ordered data  Preferred for data with unique key values

How To Implement A Dictionary

To declare a dictionary in python, we use the curly brackets. The keys and values are separated with a colon and the pairs are separated with a comma.

Operations In A Python Dictionary

1.) Accessing an element

2.) Replacing an element

3.) Removing an element

4.) Other Operations

Following are the operations we have for dictionary in python:

  • clear()
  • copy()
  • values()
  • update()
  • fromkeys()
  • get()
  • items()
  • keys()
  • pop()
  • popitem()
  • setdefault()

clear( ) – removes all the elements from the dictionary.

copy( ) – returns a copy of the dictionary.

values( ) – returns all the values in a dictionary.

update( ) – it updates the values of the dictionary with the specified key value pairs.

fromkeys( ) – returns a dictionary with the specified keys and values.

items( ) – returns the list for a tuple of each key value pair in the dictionary.

keys( ) – returns a list containing all the keys in the dictionary.

pop( ) – removes the element with the specified key.

popitem( ) – removes the last inserted key values pair from the dictionary.

setdefault( ) – returns the value of the specified key, if not present insert the key with the specified value.

Dict( ) constructor

Python dict() Function (With Example) - Trytoprogram

Dictionary constructor is used to declare a dictionary in python.

Use Case – Nested Dictionary

Nested dictionary is nothing but a dictionary which incorporates another dictionary. Let us implement a dictionary where we have the statistical data for all the Indian batsmen. We will implement a dictionary with the batsmen names and incorporate other dictionary with the statistics inside the same dictionary to make it a nested dictionary. We will also use the pandas library to get the stats into a dataframe for better understanding.

This will print the data frame of the stats of the batsmen from the dictionary. Similarly, you can make this dictionary for bowlers, all rounders and wicket keepers to practice the implementation of nested dictionary.

In this blog, we have understood the concept of dictionary in python. We have learnt to implement a dictionary and various operations that we can perform on a dictionary. We also covered dictionary constructor and nested dictionary.

Till then, Stay Safe, Stay Happy & Keep Coding…






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