r intro workshop

Intro Workshop

Saad Chahine, PhD. May 26, 2014

What is R?“R is a language and environment for statistical computing and graphics… similar to the S language and environment which was developed at Bell Laboratories… by John Chambers and colleagues…”

“R is available as Free Software under the terms of the Free Software Foundation's GNU General Public Licenses in source code form. It compiles and runs on a wide variety of UNIX platforms and similar systems (including FreeBSD and Linux), Windows and MacOS.”

http://www.r-project.org/

Getting Started

• Download and launch R

• Type help() press enter

Calculator

‘>’ is the prompt line Try: 3+5 Try: 3-5Try: 3/5Try: 3*5Try: sqrt(5)Try: sum (1,3,5)

Logic ‘>’ is the prompt line Try: 3<5 Try: 3>5Try: 3+5==8Try: 3+5==9

Variables‘<-’ assigns a value Try: x<-24 Try: xTry: x/2Try: xTry: x<-“hello world”Try: xTry: x<-TTry: x

Menu Bar

• Saving your documents • Working directories getwd()• Saving workspace

Help Example Try: help(ave)Try: help(mean)Try: help(mode)Try: help(median)Try: help(sd)Try: help(t.test)Try: help(anova)

Try: example(ave)Try: example(mean)Try: example(mode)Try: example(median)Try: example(sd)Try: example(t.test)Try: example(anova)

Vectors Try: c(3,5,7) Try: c(‘s’,’a’,’a’,’d’)Try: 3:7Try: seq(3,7)Try: seq(3,7,0.25) Try: 7:3Try: name <-c(‘s’,’a’,’a’,’d’)’Try: name [3]Try: name [3] <- ‘d’Try: name [4] <- ‘e’Try: name

Vectors Names

Try: ranks <- 1:3Try: names (ranks) <- c(“1st”,”2nd”,”3rd”, )Try: ranks Try: ranks [first]Try: ranks [3] <-4Try: scoRes <- c(450,578,502)Try: barplot(scoRes)Try: names(scoRes) <- c(“Bob”, “Marry”, “Jane”)Try: barplot (1:200)

Matrices

Try: matrix(0,6,7)Try: a<-1:42Try: print (a)Try: matrix(a,6,7)Try: seats <- 1:20Try: dim(seats) <- c(2,10) Try: print (seats)

Access Values

Try: print(seats)Try: seats[2,3] Try: seats[2,]Try: seats[1,]Try: seats[,3]Try: seats[,5:9]

Matrix Try: MATD <-matrix(1:6,2)Try: MATE <-matrix(c(rep(1,3), rep(2,3)), 2, byrow=T)Try: MATE+MATDTry: MATD+10Try: MATD-10Try: MATD+10Try: MATDTry: MATE-MATETry: MATD-MATETry: solve(MATD[,2:3])Try: t(MATE)Try: MATD %*% t(MATE)Try: MATD*100Try: MATD/MATE

Factors Try: data = c(1,2,2,3,1,3,2,2,3,3,3,2,2,1,2)Try: fdata=factor(data)Try: fdataTry: mean(data)

Import Data CSV1. Find the file path 2. mydata <-read.table(”filepath”,

header=T, sep=“,”)3. mydata <-read.table(”filepath”,

header=T, sep=“\t”)4. For fixed width use read.fwf

Import Data SPSS1. Install.packages(“m

emisc”)2. library(“memisc”)3. mydata <-

as.data.set(spss.system.file('/CSSE R Workshop/GEDU6100dataset.sav'))

4. mydata

data.frame strstr(mydata)

data.frame summarysummary(mydata)

data.frame fixfix(mydata)

Ways of calling your data- Mean

(mydata$MATH)

- With(mydata, mean(MATH))

- t.test(MATH~GENDER, data=mydata)

data.frame attachattach(mydata)mean(MATH)t.test(MATH~GENDER)

Export write.table(mydata, “filepath/mydata.txt”)

Note: for export to exl, SAS, SPSS you may need to use foreign package.

On your own

Try: data()- Find a data

set and str, summary & one statistical application

Useful Packages foreign HmiscprettyR psych ggplot2

summary(mydata describe(mydata)freq(mydata)rcorr(cbind (v1,v2,v3,v4)cor.test (v1,v2, use=“pairwise”)

Try this last one… Try: contour(volcano)Try: persp(volcano, expand=0.2)

Online resources http://tryr.codeschool.com

http://www.ats.ucla.edu/stat/r/faq/inputdata_R.htm

http://www.r-project.org/

https://www.stat.auckland.ac.nz/~paul/RGraphics/rgraphics.html

Good Luck!

saad.chahine@msvu.ca