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

Dictionaries


A dictionary can be defined as an ordered or unordered list of key-element pairs, where keys (usually unique) are used to locate elements (not necessary unique) in the data structure. For example, a data structure that stores customer information in a retail shop can be considered as a dictionary, where the consumer ID serves as the key for identification of different customers. Dictionaries are also known as associative arrays or maps, as they map keys to values to perform retrieval operations such as addition, removal, and search. Every element of a dictionary consists of a key and an associated element, also known as a key-value pair. This is shown in Figure 4.11:

Figure 4.11: Dictionary key-value pair structure

The key in a dictionary is used to differentiate between each key-value pair. It can be any randomly chosen set of values, such as real numbers or strings, with the only restriction that each key is unique, and can be differentiated from the others. The values in...