Introduction to R

1. Introduction to R
• http://cran.r-project.org/
• The Comprehensive R Archive Network
• The Base System
• The idea of Packages
• Open source Implementation of S
• Commercial implementation is S Plus
-Sujoy Bhattacharya

2. • Default Prompt is ‘>’
• setwd("C:/Documents and
Settings/USER/My Documents")
• getwd()
• ?(plot)
• R is case sensitive

3. • Objects in R: variables, arrays of numbers,
character strings, functions .
• function c()
• assignment operator (‘<-’)
• Create an object z such that: x=1 to 20,
y= 30 to 35, z= concatenation of x and y

4. • common arithmetic functions: log, exp, sin,
cos, tan, sqrt
• range()
• mean(y)=sum(y)/ length(y)
• sort(object): elements are arranged in
increasing order

5. • seq(from=5, to=50)
• seq(-4, 4, by=.1)
• z<- rep(x, times=4)
• rep(x, each=4)

6. Logical Vectors
• values :TRUE, FALSE, and NA
• <, <=, >, >=, ==(equality) != ( inequality)
• z <- x > 20
• z1 & z2 (intersection)
• z1 | z2 (union)
• !z negation of z

7. • NA and NaN
• Do 0/0 and z<- c(2,5,NA)
• Operations on NA are NA
• Do z<- c(1:100,NA)
• t<- 100*z

8. • Arrays: dim(z) <- c(3,2,2)
• z[1,1,1]
• While entering data match length
• z[1,1,]
• z <- array(1:20, dim=c(4,5))
• Z <- array(data_vector, dim_vector)

9. • object <- array(data_vector, dim_vector)
• dd <- array(data=c(1:125),c(5,5,5))
• cbind() and rbind()
• z<- cbind(c(1:10),c(1:5))
• transpose of an array: t(z)
• Matrix product : x %*% y

10. • x<- array(data=c(1:6),c(2,3))
• Matrix inversion :solve(z)
• x<- cbind(1, y, z): y,z must have equal
rows.

11. • read.csv(file.choose(), header=T)
• reg1 <- lm(y ~ x1 + x2, data = nse)
• plot(object)
• residuals(object)
• plot(x, y)

12. R communities
• www.r-project.org
• www.r-forge.r-project.org
• www.rstudio.com