Tài liệu Beginning R pptx

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Beginning R

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi

Chapter 1 Introducing R: What It Is and How to Get It . . . . . . . . . . . . . . . . . . . . . . . . . 1

Chapter 2 Starting Out: Becoming Familiar with R . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Chapter 3 Starting Out: Working With Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Chapter 4 Data: Descriptive Statistics and Tabulation . . . . . . . . . . . . . . . . . . . . . . . 107

Chapter 5 Data: Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Chapter 6 Simple Hypothesis Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

Chapter 7 Introduction to Graphical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Chapter 8 Formula Notation and Complex Statistics . . . . . . . . . . . . . . . . . . . . . . . 263

Chapter 9 Manipulating Data and Extracting Components . . . . . . . . . . . . . . . . . 295

Chapter 10 Regression (Linear Modeling) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

Chapter 11 More About Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363

Chapter 12 Writing Your Own Scripts: Beginning to Program . . . . . . . . . . . . . . . . . 415

Appendix Answers to Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461

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Beginning

R

The Statistical Pr ogramming Language

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Beginning

R

The Statistical Programming Language

Mark Gardener

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Beginning R: The Statistical Programming Language

Published by

John Wiley & Sons, Inc.

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Copyright © 2012 by John Wiley & Sons, Inc., Indianapolis, Indiana

Published simultaneously in Canada

ISBN: 978-1-118-16430-3

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It is much easier to be critical than to be correct.

— Benjamin Disraeli

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Executive Editor

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Credits

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About the Author

Mark Gardener (http://www.gardenersown.co.uk) is an ecologist,

lecturer, and writer working in the UK. He has a passion for the natu￾ral world and for learning new things. Originally he worked in optics,

but returned to education in 1996 and eventually gained his doctorate

in ecology and evolutionary biology. This work involved a lot of data

analysis, and he became interested in R as a tool to help in research.

He is currently self-employed and runs courses in ecology, data analy￾sis, and R for a variety of organizations. Mark lives in rural Devon with his wife Christine (a

biochemist), and still enjoys the natural world and learning new things.

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Acknowledgments

First of all my thanks go out to the R project team and the many authors and programmers who

work tirelessly to make this a peerless program. I would also like to thank my wife, Christine, who has

had to put up with me during this entire process, and in many senses became an R-widow! Thanks to

Wiley, for asking me to do this book, including Paul Reese, Carol Long, and Victoria Swider. I couldn’t

have done it without you. Thanks also to Richard Rowe, the technical reviewer, who first brought my

attention to R and its compelling (and rather addictive) power.

Last but not least, thanks to the R community in general. I learned to use R largely by trial and

error, and using the vast wealth of knowledge that is in this community. I hope that I have managed

to distill this knowledge into a worthy package for future devotees of R.

— Mark Gardener

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Contents

Introduction xxi

Chapter 1: Introducing R: What It Is and How to Get It 1

Getting the Hang of R 2

The R Website 3

Downloading and Installing R from CRAN 3

Installing R on Your Windows Computer 4

Installing R on Your Macintosh Computer 7

Installing R on Your Linux Computer 7

Running the R Program 8

Finding Your Way with R 10

Getting Help via the CRAN Website and the Internet 10

The Help Command in R 10

Help for Windows Users 11

Help for Macintosh Users 11

Help for Linux Users 13

Help For All Users 13

Anatomy of a Help Item in R 14

Command Packages 16

Standard Command Packages 16

What Extra Packages Can Do for You 16

How to Get Extra Packages of R Commands 18

How to Install Extra Packages for Windows Users 18

How to Install Extra Packages for Macintosh Users 18

How to Install Extra Packages for Linux Users 19

Running and Manipulating Packages 20

Loading Packages 21

Windows-Specific Package Commands 21

Macintosh-Specific Package Commands 21

Removing or Unloading Packages 22

Summary 22

Chapter 2: Starting Out: Becoming Familiar with R 25

Some Simple Math 26

Use R Like a Calculator 26

Storing the Results of Calculations 29

Contents

Chapter 1: Credit

Chapter 2: About the Author

Chapter 3: Acknowledgment

ion

Who This Book Is For

Is Structured

Need to Use This Book

Errata

Chapter 4: Introducing R: What It Is and How to Get It

Getting the Hang of R

Chapter 5: Starting Out: Becoming Familiar with R

Getting Data into R

Named Objects

Items

Items

Examining Data Structure

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xii

CONTENTS Reading and

Getting Data into R 30

Using the combine Command for Making Data 30 Entering Numerical Items as Data 30 Entering Text Items as Data 31 Using the scan Command for Making Data 32 Entering Text as Data 33 Using the Clipboard to Make Data 33 Reading a File of Data from a Disk 35 Reading Bigger Data Files 37 The read.csv() Command 37 Alternative Commands for Reading Data in R 39 Missing Values in Data Files 40

Viewing

Named Objects 41

Viewing Previously Loaded Named-Objects 42 Viewing All Objects 42 Viewing Only Matching Names 42 Removing Objects from R 44

Types of Data

Items 45

Number Data 45 Text Items 45

Converting Between Number and Text Data 46

The Structure of Data

Items 47

Vector Items 48 Data Frames 48 Matrix Objects 49 List Objects 49

Examining Data Structure 49 Working with History Commands 51

Using History Files 52 Viewing the Previous Command History 52 Saving and Recalling Lists of Commands 52 Alternative History Commands in Macintosh OS 52 Editing History Files 53

Saving Your Work in R 54

Saving the Workspace on Exit 54 Saving Data Files to Disk 54 Save Named Objects 54 Save Everything 55 Reading Data Files from Disk 56 Saving Data to Disk as Text Files 57 Writing Vector Objects to Disk 58 Writing Matrix and Data Frame Objects to Disk 58

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xiii

CONTENTS Writing List Objects to Disk 59

Converting List Objects to Data Frames 60

Summary 61

Chapter 3: Starting Out: Working

With Ob jects 65

Manipulating Objects 65

Manipulating Vectors 66

Selecting and Displaying Parts of a Vector 66

Sorting and Rearranging a Vector 68

Returning Logical Values from a Vector 70

Manipulating Matrix and Data Frames 70

Selecting and Displaying Parts of a Matrix or Data Frame 71

Sorting and Rearranging a Matrix or Data Frame 74

Manipulating Lists 76

Viewing Objects within Objects 77

Looking Inside Complicated Data Objects 77

Opening Complicated Data Objects 78

Quick Looks at Complicated Data Objects 80

Viewing and Setting Names 82

Rotating Data Tables 86

Constructing Data Objects 86

Making Lists 87

Making Data Frames 88

Making Matrix Objects 89

Re-ordering Data Frames and Matrix Objects 92

Forms of Data Objects: Testing and Converting 96

Testing to See What Type of Object You Have 96

Converting from One Object Form to Another 97

Convert a Matrix to a Data Frame 97

Convert a Data Frame into a Matrix 98

Convert a Data Frame into a List 99

Convert a Matrix into a List 100

Convert a List to Something Else 100

Summary 104

Chapter 4: Data: Descriptive Statistics and Tabulation 107

Summary Commands 108

Summarizing Samples 110

Summary Statistics for Vectors 110

Summary Commands With Single Value Results 110

Summary Commands With Multiple Results 113

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