Installing R

1
Installing R

• CRAN http//cran.r-project.org/
• (R homepage http//www.r-project.org/)
• Windows 95 and later ? Base
• rw2001.exe

2
Editors for R

• WinEdt
• www.winedt.com
• Download winedt 5.3 or 5.4
• RWinEdt package
• http//cran.r-project.org/ ? Other ? Editing
  Support ? R-WinEdt
• Download most recent zip file
• Packages ? Install package(s) from local zip
  files
• Library(RWinEdt)
• To make automatic R? rw2001 ? etc ? Rprofile
• Type commands, highlight, R-Paste
• Use for comments
• Free for about 100 uses, student license is 30
• EMACS
• www.xemacs.org
• ESS package
• Free!

3
General

• R workspace
• Show whats been stored ls() or objects()
• Remove individual objects rm(a, b, etc.)
• Clear entire workspace rm(listls())
• Quit q() or file ? exit
• Save workspace?
• Where to store R files file ? change directory
• File ? load workspace or save workspace
• save() or save.image()
• Up arrow repeats prior commands
• R is case sensitive
• gt start new command finish command
• Customize R
• Options()
• Edit ? GUI preferences

4
Assignments and some basic math

• The assignment operator consists of lt and -
  and points from the expression to the name given
  to that expression
• x lt- 10 assigns the number 10 to the letter x
• Assignments can be made in either direction
• R as an over-qualified calculator
• Log, exp
• Mean, median, mode, max, min, sd
• Trigonometry
• Set operations
• Logical operators lt, lt, gt, gt, , !

5
Vectors

• Vectors have length, but no dimension
• gtlength(vector)
• c() concatenates or combines numbers inside ()
  into a vector or list
• seq() generates sequence
• Can specify length of sequence and increment
• rep() replicates elements
• gtsort(vector) sorts items in vector
• Can use usual arithmetic and mathematical
  functions on vectors
• Logical vectors
• Character vectors
• Indexing a vector
• gtvectori

6
Matrices

• Matrices have length and dimensions
• gtlength(M) dim(M)
• Generating matrices
• By combining vectors rbind() cbind()
• gtmatrix() command
• Transpose
• gtt(M)
• Diagonal
• gtdiag(M)
• Inverse
• gtsolve(M)
• Multiplying matrices MN
• Indexing matrices

7
Some simple functions

• Writing a user function
• gtfunction( argument list )expressions
• Expressions or commands can be grouped together
  in , as they often are when writing functions.
  The value of the grouped commands is the result
  of the last expression.
• Conditionals
• if, else
• Loops
• for

8
Probability distributions

• norm, binom, beta, cauchy, chisq, exp, f, gamma,
  geom, hyper, lnorm, logis, nbinom, t, unif,
  weibull, wilcox
• Four prefixes
• d for density (PDF)
• p for distribution (CDF)
• q for quantile (percentiles)
• r for random generation (simulation)
• Each distribution has arguments that need to be
  specified

9
Loading

• Stata, SPSS, SAS files
• Library(foreign)
• Stata read.dta
• SPSS read.spss
• SAS read.xport (must first create export file in
  SAS)
• Excel files
• Files must be saved as comma separated value or
  .csv
• read.table, read.csv, read.csv2 identical except
  for defaults
• Watch the direction of /!
• gtload(.Rdata)
• Loading and running R programs
• gtsource(.R)

10
Data

• gtsummary(data)
• gtnames(data) gtattributes(data)
• Editing data
• gtfix(data) or gtedit(data)
• gtdatavar
• gtattach(data) in order to remove need of
• gtdetach(data)

11
NA, NaN, and Null

• NA or Not Available
• Applies to many modes character, numeric, etc.
• NaN or Not a Number
• Applies only to numeric modes
• NULL
• Lists with zero length

12
Lm, glm, nlm, optim

• Linear models
• gtlm(yx1x2)
• Generalized linear models
• gtglm(yx1x2, family)
• See help(family) for family options family
  specifies error distribution
• Non-linear minimization
• gtnlm(f, p) where f is the function to be
  minimized and p are the starting parameters
• Optimization
• gtoptim(par, fn) where par are the initial values
  and fn is the function to be minimized

13
Graphics

• gtpar() is used to set graphical options
• mfrow and mfcol
• gtplot(x,y)
• gtidentify() gtabline()
• Arguments type, point style, labels, etc.
• Boxplot, histograms, sunflowerplots, piecharts,
  etc.
• Saving them
• As .pdf or .ps files
• gtdev.off()
• Know the current directory

14
Help!

• gthelp(packagestats)
• Lists functions in the specified package
• gthelp(glm) or gt?glm
• gthelp() for characters
• Help ? Html help ? Search Engine Keywords
• Potentially most helpful
• R documentation
• commandpackage

15
Other Resources

• The R Manuals under Documentation at
  http//www.r-project.org
• Mark Handcocks website at http//www.stat.washing
  ton.edu/handcock/567/links.html
• Jonathan Barrons R resources at
  http//finzi.psych.upenn.edu/
• Fox, John. 2002. An R and S-PLUS Companion to
  Applied Regression
• Cori Mar is teaching an intro to R class in the
  main CSSCR lab on Wednesday from 330-5