What are the Important Data Structures and Algorithms in Python?

• In this article you will learn:
• 1.Important Data Structures in Python.
• 2.Algorithm.
• 3.Conclusion.

Important Data Structures in Python:

Lists:

Python Lists are the ordered collections of a data just like arrays in the other programming languages. It allows a various types of elements in the list. The implementation of a Python List is similar to Vectors in C++ or ArrayList in JAVA. The costly operation is an inserting or deleting the element from a beginning of the List as all elements are needed to be shifted. An Insertion and deletion at end of the list can also become costly in case where a preallocated memory becomes full.

Example: Creating Python List

Python3

List elements can be accessed by a assigned index. In a python starting index of the list, a sequence is 0 and an ending index is (if N elements are there) N-1.

Tuple:

• Python tuples are similar to the lists but Tuples are immutable in nature i.e. once created it cannot be a modified. Just like List, a Tuple can also contain elements of different types.
• In a Python, tuples are created by a placing a sequence of values separated by ‘comma’ with or without use of a parentheses for grouping of the data sequence.
• To create tuple of one element there must be trailing comma. For example, (8,) will create tuple containing 8 as a element.

Set:

• Python set is the mutable collection of data that does not allow the any duplication. Sets are basically used to include the membership testing and eliminating a duplicate entries. The data structure used in this Hashing, a famous technique to perform insertion, deletion, and traversal in O(1) on a average.
• If a Multiple values are present at a same index position, then value is appended to that index position, to form Linked List. In, CPython Sets are implemented using dictionary with a dummy variables, where key beings members set with greater optimizations to time complexity.

Frozen Sets:

Frozen sets in a Python are immutable objects that are only support methods and operators that produce result without affecting a frozen set or sets to which they are be applied. While elements of set can be modified at a any time, elements of the frozen set remain a same after creation.

String:

• Python Strings is an immutable array of a bytes representing Unicode characters. Python does not have character data type, a single character is simply a string with the length of 1.
• As strings are be immutable, modifying a string will result in a creating new copy.

Dictionary:

Python dictionary is the unordered collection of data that saves data in a format of key:value pair. It is like hash tables in the any other language with a time complexity of O(1). Indexing of a Python Dictionary is done with help of keys. These are of any hashable type i.e. an object whose can never change like a strings, numbers, tuples, etc. Can create a dictionary by using a curly braces ({}) or dictionary comprehension.

Matrix:

A matrix is the 2D array where each element is of a strictly the same size. To create matrix will be using a NumPy package.

Bytearray:

Python Bytearray gives the mutable sequence of an integers in range 0 <= x < 256.

Linked List:

A linked list is the linear data structure in which an elements are not stored at a contiguous memory locations. The elements in a linked list are linked using a pointers A linked list is be represented by a pointer to first node of the linked list. The first node is called head. If linked list is empty, then value of the head is a NULL. Every node in the list consists of at least two parts:

• Data.
• Pointer (Or Reference) to the next node.

Linked List Traversal:

In a previous program, have created a simple linked list with the three nodes. Let us traverse a created list and print the data of every node. For traversal, let us write general-purpose function of printList() that prints any given list.

Stack:

A stack is the linear data structure that stores items in the Last-In/First-Out (LIFO) or First-In/Last-Out (FILO) manner. In a stack, a new element is added at a one end and an element is removed from that end only. The insert and delete operations are be often called a push and pop.

Queue:

As a stack, a queue is a linear data structure that saves an items in a First In First Out (FIFO) manner. With queue, the least recently added item is a removed first. A good example of a queue is any queue of the consumers for a resource where a consumer that came first is served first.

Binary Tree:

The topmost node of a tree is called the root whereas bottommost nodes or the nodes with the no children are called the leaf nodes. The nodes that are be directly under a node are called its a children and the nodes that are directly above something are called its be a parent.A binary tree is the tree whose elements can have almost a two children. Since every element in a binary tree can have only a 2 children, typically name them a left and right children. A Binary Tree node contains a following parts.

• Data.
• Pointer to left child.
• Pointer to the right child.

Algorithm:

Algorithm Inorder(tree):

• Traverse a left subtree i.e. call Inorder(left-subtree).
• Visit a root.
• Traverse a right subtree i.e. call Inorder(right-subtree).

Algorithm Preorder(tree):

• Visit a root.
• Traversea left subtree i.e. call Preorder(left-subtree).
• Traverse a right subtree i.e. call Preorder(right-subtree).

Algorithm Postorder(tree):

• Traverse a left subtree i.e. call Postorder(left-subtree).
• Traverse a right subtree i.e. call Postorder(right-subtree).
• Visit a root.

Conclusion:

Data structures deal with how a data is organised and held in memory, when a program processes it. It is an important to note that, the data that is saved in a disk as part of persistent storages (like relational tables) are not referred as a data structure here.An Algorithm is step by step set of an instruction to process the data for a particular purpose. So, an algorithm utilises a different data structures in a logical way to solve the specific computing problem.