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

Quick sort


The quick sort algorithm is an updated version of the merge sort algorithm with faster in-memory sorting capability. It is widely used in average-case as against worst-case scenarios. It is also efficient in terms of memory utilization, as it does not require the secondary vector when performing the merge operation. Quick sort can be accessed in R using functions such as sort (base) and quick sort (rje). It is also called partition-exchange sort. Like merge sort, quick sort also requires recursive implementation for effective execution.

The following is the three-step execution methodology of the quick sort algorithm for a given input vector V with n elements:

  1. Select the pivot or root element of the given input vector. The pivot element is used to partition the entire vector into two subvectors such that all the elements in the first vector or left vector are less than the pivot, and all the elements in the second vector or right vector are greater than or equal to the pivot. However...