1. R Scripting Environment¶
1.1. Getting Help¶
help on a function:
> help(rnorm)
Examples of using a function:
> example(rnorm)
Starting global help:
> help.start()
1.2. Workspace¶
List of objects in workspace:
> ls()
We can also use objects function:
> objects()
Clear all variables from workspace:
> rm(list=ls())
Clear a variable from workspace:
> rm(a)
Clearing the console:
> cat("\014")
1.3. Arithmetic¶
Addition:
> 2 + 3
[1] 5
Subtraction:
> 2 - 3
[1] -1
Negation:
> -8
[1] -8
Multiplication:
> 2 * 3
[1] 6
Division:
> 8 / 3
[1] 2.666667
> 8 / -3
[1] -2.666667
Integer division:
> 8 %/% 3
[1] 2
> -8 %/% 3
[1] -3
> 8 %/% -3
[1] -3
> -8 %/% -3
[1] 2
Remainder:
> 8 %% 3
[1] 2
> -8 %% 3
[1] 1
> 8 %% -3
[1] -1
> -8 %% -3
[1] -2
Let us combine integer division and remainder:
> 2 * 3 + 2
[1] 8
> -3 * 3 + 1
[1] -8
> (-3) * (-3) + (-1)
[1] 8
> (2) * (-3) + (-2)
[1] -8
Exponentiation:
> 10^1
[1] 10
> 11^2
[1] 121
> 11^3
[1] 1331
Some more complicated expressions
> 10^2 + 36
Compounded interest over a number of years:
> 1000 * (1 + 10/100)^5
[1] 1610.51
1.4. Variables¶
Assignment:
> a=4
> a<-4
> 3 -> a
> a
[1] 3
Display:
> a
Use:
> a*5
> a=a+10
> a<-a+10
Assignment through function:
> assign("x", c(1.4, 2.3, 4.4))
> x
[1] 1.4 2.3 4.4
Assignments in other direction:
2 -> x
1.5. Data Types¶
A vector:
> x <- c(1, 2, 3)
> x
[1] 1 2 3
> x[1]
[1] 1
> x[1:2]
[1] 1 2
A sequence:
> x <- 1:4
> x
[1] 1 2 3 4
A matrix:
> x <- matrix(1:4, nrow=2)
> x
[,1] [,2]
[1,] 1 3
[2,] 2 4
An array:
> x <- array(1:16, dim=c(2,2,4))
> x[1,1,1]
[1] 1
> x[1,2,1]
[1] 3
> x[1,2,3]
[1] 11
A character vector or string:
x <- "hello"
A list:
> x <- list(a=4, b=2.4, c="hello")
> x$a
[1] 4
> x$b
[1] 2.4
> x$c
[1] "hello"
A data frame:
> frm <- data.frame(x=c(1,2,3), y=c(21, 20, 23), z=c("a", "b", "c"))
> frm$x
[1] 1 2 3
> frm$y
[1] 21 20 23
> frm$z
[1] a b c
Levels: a b c
> frm[1,]
x y z
1 1 21 a
Extended arithmetic with vectors:
> 11 ^ c(1,2,3,4)
[1] 11 121 1331 14641
> c(1,2,3,4) ^ 3
[1] 1 8 27 64
> c(1,2,3) * c(2,3,4)
[1] 2 6 12