Book Image

R Data Structures and Algorithms

By : PKS Prakash, Achyutuni Sri Krishna Rao
Book Image

R Data Structures and Algorithms

By: PKS Prakash, Achyutuni Sri Krishna Rao

Overview of this book

In this book, we cover not only classical data structures, but also functional data structures. We begin by answering the fundamental question: why data structures? We then move on to cover the relationship between data structures and algorithms, followed by an analysis and evaluation of algorithms. We introduce the fundamentals of data structures, such as lists, stacks, queues, and dictionaries, using real-world examples. We also cover topics such as indexing, sorting, and searching in depth. Later on, you will be exposed to advanced topics such as graph data structures, dynamic programming, and randomized algorithms. You will come to appreciate the intricacies of high performance and scalable programming using R. We also cover special R data structures such as vectors, data frames, and atomic vectors. With this easy-to-read book, you will be able to understand the power of linked lists, double linked lists, and circular linked lists. We will also explore the application of binary search and will go in depth into sorting algorithms such as bubble sort, selection sort, insertion sort, and merge sort.
Table of Contents (17 chapters)
R Data Structures and Algorithms
Credits
About the Authors
Acknowledgments
About the Reviewer
www.PacktPub.com
Preface

Heap sort


Heap sort is an improvised form of selection sort, wherein the algorithm initially splits the input vector into sorted and unsorted vectors, and then iteratively shrinks the unsorted vector by extracting the largest element and placing it in the sorted vector. It is based on the heap data structure which provides a non-quadratic asymptote even for the worst-case scenarios. Heaps are tree-based data structures with the following properties:

  • Shape criterion: Heaps are primarily complete binary trees with both the left and right child nodes filled with values:

    Figure 5.10: Illustration of complete and in-complete binary tree

  • Heap criterion: The ordering of the tree is unidirectional. In other words, all the parent nodes will be greater than the child nodes (max-heap), or all the child nodes will be greater than the parent nodes (min-heap). Either of the heaps can be used for sorting in any required order. In our example, we will use max-heap to sort the input vector in an ascending...