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

Three Θ(n²) sorting algorithms


The following sections deal with three different sorting algorithms, which require θ(n2 ) system runtime to execute both average-and worst-case scenarios. These algorithms are simple to implement, but show poor computational performance.

Insertion sort

Consider a vector V of numeric elements which needs to be sorted in ascending order. The most intuitive way is to iterate through the vector of elements and then perform element insertions at relevant positions within the vector, satisfying the ordering criterion. This kind of ordering based on a series of insertions is termed insertion sorting. The following Figure 5.1 illustrates the approach for insertion sorting in which each row represents the modified vector for the corresponding ith iteration. The sorting operation is indicated by the arrows:

Figure 5.1: Illustration of insertion sort

The following is the code in R which performs insertion sorting to arrange a vector in increasing order:

Insertion_Sort ...