Ruby Data Processing : Using Map, Reduce, and Select

Gain the basics of Ruby’s map, reduce, and select functions and discover how to use them to solve data-processing problems. This compact hands-on book explains how you can encode certain complex programs in 10 lines of Ruby code, an astonishingly small number. You will walk through problems and solutions which are effective because they use map, reduce, and select. As you read __Ruby Data Processing__, type in the code, run the code, and ponder the results. Tweak the code to test the code and see how the results change. After reading this book, you will have a deeper understanding of how to break data-processing problems into processing stages, each of which is understandable, debuggable, and composable, and how to combine the stages to solve your data-processing problem. As a result, your Ruby coding will become more efficient and your programs will be more elegant and robust. **What You Will Learn** * Discover Ruby data processing and how to do it using the map, reduce, and select functions * Develop complex solutions including debugging, randomizing, sorting, grouping, and more * Reverse engineer complex data-processing solutions **Who This Book Is For** Those who have at least some prior experience programming in Ruby and who have a background and interest in data analysis and processing using Ruby. Table of Contents 4 About the Author 6 About the Technical Reviewer 7 Acknowledgments 8 Introduction 9 Prerequisites 12 Chapter 1: Basic Ruby 13 The Command Line 13 Object Scope 15 String 16 Array 18 Special Methods 18 Hash 20 Block-passing Syntax 21 Reading from Files 23 Chapter 2: Function Overview and Simple Examples 25 Map 25 Reduce 27 Simple Reduce Examples 31 uniq 31 reverse 32 max 33 Select 35 Chapter 3: Complex Solutions 37 Debugging Blocks for Map, Reduce, and Select 37 Debugging Map Blocks 37 Debugging Reduce Blocks 38 Debugging Select Blocks 39 FizzBuzz 39 Sum of Odd Cubes 42 Sort a List of Names by Surname 45 Convert a List of Names to CSV 48 Generate a Random List of Names 51 Clean a Data Set 54 Annotate a Sequence of Sales with Running Total 58 Pascal’s Triangle 60 Reverse Polish Notation Parser 67 Generate a List of Team Name Bars 74 Find Intersection Points of Two Functions 79 Group by Area Code 87 Sliding Window Average 89 Denormalize a Data Set 94 Pythagorean Triplets 96 Chapter 4: Reverse-Engineering Complex Solutions 101 Solution for Pascal’s Triangle 102 Index 109 "Gain the basics of Ruby's map, reduce, and select functions and discover how to use them to solve data-processing problems. This compact hands-on book explains how you can encode certain complex programs in 10 lines of Ruby code, an astonishingly small number. You will walk through problems and solutions which are effective because they use map, reduce, and select. As you read Ruby Data Processing, type in the code, run the code, and ponder the results. Tweak the code to test the code and see how the results change. After reading this book, you will have a deeper understanding of how to break data-processing problems into processing stages, each of which is understandable, debuggable, and composable, and how to combine the stages to solve your data-processing problem. As a result, your Ruby coding will become more efficient and your programs will be more elegant and robust."-- Provided by publisher Front Matter ....Pages i-xv Basic Ruby (Jay Godse)....Pages 1-12 Function Overview and Simple Examples (Jay Godse)....Pages 13-24 Complex Solutions (Jay Godse)....Pages 25-88 Reverse-Engineering Complex Solutions (Jay Godse)....Pages 89-96 Back Matter ....Pages 97-98 Walking you through several problems and solutions, this hands-on book will teach you the basics of Rubys map, reduce, and select functions, and will show how to use them to solve data-processing problems. -- Edited summary from book