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R Intro Workshop


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This is an Intro R work shop for graduate students at CSSE

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R Intro Workshop

  1. 1. Intro Workshop Saad Chahine, PhD. May 26, 2014
  2. 2. 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.”
  3. 3. Getting Started • Download and launch R • Type help() press enter
  4. 4. Calculator ‘>’ is the prompt line Try: 3+5 Try: 3-5 Try: 3/5 Try: 3*5 Try: sqrt(5) Try: sum (1,3,5)
  5. 5. Logic ‘>’ is the prompt line Try: 3<5 Try: 3>5 Try: 3+5==8 Try: 3+5==9
  6. 6. Variables ‘<-’ assigns a value Try: x<-24 Try: x Try: x/2 Try: x Try: x<-“hello world” Try: x Try: x<-T Try: x
  7. 7. Menu Bar • Saving your documents • Working directories getwd() • Saving workspace
  8. 8. 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)
  9. 9. Vectors Try: c(3,5,7) Try: c(‘s’,’a’,’a’,’d’) Try: 3:7 Try: seq(3,7) Try: seq(3,7,0.25) Try: 7:3 Try: name <-c(‘s’,’a’,’a’,’d’)’ Try: name [3] Try: name [3] <- ‘d’ Try: name [4] <- ‘e’ Try: name
  10. 10. Vectors Names Try: ranks <- 1:3 Try: names (ranks) <- c(“1st”,”2nd”,”3rd”, ) Try: ranks Try: ranks [first] Try: ranks [3] <-4 Try: scoRes <- c(450,578,502) Try: barplot(scoRes) Try: names(scoRes) <- c(“Bob”, “Marry”, “Jane”) Try: barplot (1:200)
  11. 11. Matrices Try: matrix(0,6,7) Try: a<-1:42 Try: print (a) Try: matrix(a,6,7) Try: seats <- 1:20 Try: dim(seats) <- c(2,10) Try: print (seats)
  12. 12. Access Values Try: print(seats) Try: seats[2,3] Try: seats[2,] Try: seats[1,] Try: seats[,3] Try: seats[,5:9]
  13. 13. Matrix Try: MATD <-matrix(1:6,2) Try: MATE <-matrix(c(rep(1,3), rep(2,3)), 2, byrow=T) Try: MATE+MATD Try: MATD+10 Try: MATD-10 Try: MATD+10 Try: MATD Try: MATE-MATE Try: MATD-MATE Try: solve(MATD[,2:3]) Try: t(MATE) Try: MATD %*% t(MATE) Try: MATD*100 Try: MATD/MATE
  14. 14. Factors Try: data = c(1,2,2,3,1,3,2,2,3,3,3,2,2,1,2) Try: fdata=factor(data) Try: fdata Try: mean(data)
  15. 15. Import Data CSV 1. 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
  16. 16. Import Data SPSS 1. Install.packages(“me misc”) 2. library(“memisc”) 3. mydata <- em.file('/CSSE R Workshop/GEDU6100 dataset.sav')) 4. mydata
  17. 17. data.frame str str(mydata)
  18. 18. data.frame summary summary(mydata)
  19. 19. data.frame fix fix(mydata)
  20. 20. Ways of calling your data - Mean (mydata$MATH) - With(mydata, mean(MATH)) - t.test(MATH~GENDER, data=mydata)
  21. 21. data.frame attach attach(mydata) mean(MATH) t.test(MATH~GENDER)
  22. 22. Export write.table(mydata, “filepath/mydata.txt”) Note: for export to exl, SAS, SPSS you may need to use foreign package.
  23. 23. On your own Try: data() - Find a data set and str, summary & one statistical application
  24. 24. Useful Packages foreign Hmisc prettyR psych ggplot2 summary(mydata describe(mydata) freq(mydata) rcorr(cbind (v1,v2,v3,v4) cor.test (v1,v2, use=“pairwise”)
  25. 25. Try this last one… Try: contour(volcano) Try: persp(volcano, expand=0.2)
  26. 26. Online resources
  27. 27. Good Luck!