4+ 3 / 5^2
## [1] 4.12
rnorm(4, mean = 10, sd = 2)
## [1] 10.557544 12.668861 9.653690 7.821869
mean(sample(1:10, 5))
## [1] 5.4
plot(x=sample(1:10,5),y=sample(1:10,5),
main="Five random points",xlab="X values",ylab="Y values")
vat <- 0.2;vat
## [1] 0.2
vat
## [1] 0.2
y <- 39
y
## [1] 39
y <- 43
y
## [1] 43
z <- 5
w <- z^2
w
## [1] 25
i <- (z * 2 +45)/2
i
## [1] 27.5
ls()
## [1] "i" "vat" "w" "y" "z"
objects()
## [1] "i" "vat" "w" "y" "z"
rm(vat,y,z,w,i)
rm(list=ls())
max(4, 5, 6, 12, -4)
## [1] 12
max(sample(1:100, 30))
## [1] 100
exists("w")
## [1] FALSE
exists("se")
## [1] FALSE
se<- function(x) {
v<- var(x)
n<- length(x)
return(sqrt(v/n))
}
se(x=sample(20:100,50))
## [1] 3.420724
exists("se")
## [1] TRUE
#function(<set of parameters>) { <set of R instructions> }
mySample <- rnorm(100, mean=20, sd=4)
se(mySample)
## [1] 0.4157936
convMeters <- function(val,to="inch") {
mult <- switch(to,foot=3.28084,inch=39.3701,yard=1.09361,mile=0.000621371,NA)
if (is.na(mult)) stop("Unknown target unit of length.")
else return(val*mult)
}
convMeters(23,"foot")
## [1] 75.45932
convMeters(40,"inch")
## [1] 1574.804
convMeters(40)
## [1] 1574.804
convMeters(56.2,"yard")
## [1] 61.46088
convMeters(to="yard",val=56.2)
## [1] 61.46088
convMeters(56.2,to="yard")
## [1] 61.46088
v <- c(4, 7, 23.5, 76.2, 80)
length(v)
## [1] 5
mode(v)
## [1] "numeric"
v <- c(4, 7, 23.5, 76.2, 80, "rrt")
mode(v)
## [1] "character"
v[5]
## [1] "80"
x <- vector()
x[3] <- 45
x
## [1] NA NA 45
v <- c(45, 243, 78, 343, 445, 44, 56, 77);v
## [1] 45 243 78 343 445 44 56 77
v <- c(v[5], v[7]);v
## [1] 445 56
v1 <- c(4, 6, 87)
v2 <- c(34, 32.4, 12)
v1 + v2
## [1] 38.0 38.4 99.0
2 * v1
## [1] 8 12 174
g <- c("f", "m", "m", "m", "f", "m", "f", "m", "f", "f")
g
## [1] "f" "m" "m" "m" "f" "m" "f" "m" "f" "f"
g <- factor(g)
g
## [1] f m m m f m f m f f
## Levels: f m
g[3]
## [1] m
## Levels: f m
g[3] == "m"
## [1] TRUE
other.g <- factor(c("m", "m", "m", "m", "m"), levels = c("f","m"))
other.g
## [1] m m m m m
## Levels: f m
table(g)
## g
## f m
## 5 5
table(other.g)
## other.g
## f m
## 0 5
a <- factor(c('adult','adult','juvenile','juvenile','adult',
'adult','adult','juvenile','adult','juvenile'))
table(a, g)
## g
## a f m
## adult 4 2
## juvenile 1 3
t <- table(a, g)
margin.table(t, 1)
## a
## adult juvenile
## 6 4
margin.table(t, 2)
## g
## f m
## 5 5
dim(t)
## [1] 2 2
prop.table(t, 1)
## g
## a f m
## adult 0.6666667 0.3333333
## juvenile 0.2500000 0.7500000
prop.table(t, 2)
## g
## a f m
## adult 0.8 0.4
## juvenile 0.2 0.6