Ciencia

An Introduction to R
Notes on R: A Programming Environment for Data Analysis and Graphics Version 2.15.2 (2012-10-26)

W. N. Venables, D. M. Smith and the R Core Team

Copyright Copyright Copyright Copyright Copyright

c c c c c

1990 W. N. Venables 1992 W. N. Venables & D. M. Smith 1997 R. Gentleman & R. Ihaka 1997, 1998 M. Maechler 1997– R Core Team

Copyright c 1999–2012 R CoreTeam

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identicalto this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the R Core Team. ISBN 3-900051-12-7

i

Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1 Introduction and preliminaries . . . . . . . . . . . . . . . . 2
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 The R environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Related software and documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . R and statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . R and the window system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Using R interactively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . An introductory session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Getting help with functions and features . . . . . . . . . . .. . . . . . . . . . . . . R commands, case sensitivity, etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recall and correction of previous commands . . . . . . . . . . . . . . . . . . . . Executing commands from or diverting output to a file . . . . . . . . Data permanency and removing objects . . . . . . . . . . . . . . . . . . . . . . . 2 2 2 3 3 4 4 5 5 6 6

2

Simplemanipulations; numbers and vectors . . 7
2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Vectors and assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Vector arithmetic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Generating regular sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Logicalvectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Missing values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Character vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Index vectors; selecting and modifying subsets of a data set . . . . 11Other types of objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3

Objects, their modes and attributes . . . . . . . . . 13
3.1 3.2 3.3 3.4 Intrinsic attributes: mode and length . . . . . . . . . . . . . . . . . . . . . . . . . . Changing the length of an object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Getting and settingattributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The class of an object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 14 14 15

4

Ordered and unordered factors . . . . . . . . . . . . . . . 16
4.1 A specific example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.2 The function tapply()...