Book Image

Java: Data Science Made Easy

By : Richard M. Reese, Jennifer L. Reese, Alexey Grigorev
Book Image

Java: Data Science Made Easy

By: Richard M. Reese, Jennifer L. Reese, Alexey Grigorev

Overview of this book

Data science is concerned with extracting knowledge and insights from a wide variety of data sources to analyse patterns or predict future behaviour. It draws from a wide array of disciplines including statistics, computer science, mathematics, machine learning, and data mining. In this course, we cover the basic as well as advanced data science concepts and how they are implemented using the popular Java tools and libraries.The course starts with an introduction of data science, followed by the basic data science tasks of data collection, data cleaning, data analysis, and data visualization. This is followed by a discussion of statistical techniques and more advanced topics including machine learning, neural networks, and deep learning. You will examine the major categories of data analysis including text, visual, and audio data, followed by a discussion of resources that support parallel implementation. Throughout this course, the chapters will illustrate a challenging data science problem, and then go on to present a comprehensive, Java-based solution to tackle that problem. You will cover a wide range of topics – from classification and regression, to dimensionality reduction and clustering, deep learning and working with Big Data. Finally, you will see the different ways to deploy the model and evaluate it in production settings. By the end of this course, you will be up and running with various facets of data science using Java, in no time at all. This course contains premium content from two of our recently published popular titles: - Java for Data Science - Mastering Java for Data Science
Table of Contents (29 chapters)
Title Page
Credits
Preface
Free Chapter
1
Module 1
15
Module 2
26
Bibliography

Standard deviation


Standard deviation is a measurement of how values are spread around the mean. A high deviation means that there is a wide spread, whereas a low deviation means that the values are more tightly grouped around the mean. This measurement can be misleading if there is not a single focus point or there are numerous outliers.

We begin by showing a simple example using basic Java techniques. We are using our testData array from previous examples, duplicated here:

double[] testData = {12.5, 18.3, 11.2, 19.0, 22.1, 14.3, 16.2, 12.5,
   17.8, 16.5, 11.2}; 

Before we can calculate the standard deviation, we need to find the average. We could use any of our techniques listed in the Calculating the mean section, but we will add up our values and divide by the length of testData for simplicity's sake:

int sum = 0; 
for(double value : testData){ 
   sum += value; 
} 
double mean = sum/testData.length; 

Next, we create a variable, sdSum, to help us calculate the standard deviation. As...