Test 1

# Questions on Exam
se <- function(x){
  v <- var(x)
  n <- length(x)
  return(sqrt(v/n))
}

MySample <- rnorm(10,mean=0,sd=1)
se(MySample)

## [1] 0.2503053

x<-factor(c('adult','adult','height','weight','adult','weight','weight','height'))
x

## [1] adult  adult  height weight adult  weight weight height
## Levels: adult height weight

table(x)

## x
##  adult height weight 
##      3      2      3

rep(12,6)

## [1] 12 12 12 12 12 12

gl(3,4)

##  [1] 1 1 1 1 2 2 2 2 3 3 3 3
## Levels: 1 2 3

results <-  matrix(c(10, 30, 50, 43, 56, 21, 30),  2, 4,  byrow = TRUE)

## Warning in matrix(c(10, 30, 50, 43, 56, 21, 30), 2, 4, byrow = TRUE): data
## length [7] is not a sub-multiple or multiple of the number of rows [2]

a <- c(-8, -3, 0, 5, 10, 21, 30)
a

## [1] -8 -3  0  5 10 21 30

a[a  <= 0  |  a >  10]

## [1] -8 -3  0 21 30

a[c(3, 6)]

## [1]  0 21

a <- c(-8, -3, 0, 5, 10, 21, 30)
a[  -3]

## [1] -8 -3  5 10 21 30

a[ - (1:4)]

## [1] 10 21 30

g <- c(67, 78, 45, 87, 57, 98, 95, 83, 74, 80, 55, 49)
g

##  [1] 67 78 45 87 57 98 95 83 74 80 55 49

g <- matrix(c( 67, 78, 45, 87, 57, 98, 95, 83, 74, 80, 55, 49), 3, 4)
g

##      [,1] [,2] [,3] [,4]
## [1,]   67   87   95   80
## [2,]   78   57   83   55
## [3,]   45   98   74   49

g <- matrix(c( 67, 78, 45, 87, 57, 98, 95, 83, 74, 80, 55, 49), 3, 4, byrow = TRUE)
g

##      [,1] [,2] [,3] [,4]
## [1,]   67   78   45   87
## [2,]   57   98   95   83
## [3,]   74   80   55   49

g[ 2,  , drop = FALSE]

##      [,1] [,2] [,3] [,4]
## [1,]   57   98   95   83

g[  , 3,  drop = FALSE]

##      [,1]
## [1,]   45
## [2,]   95
## [3,]   55

g1 <-  matrix(c( 67, 78, 45, 87, 57, 98, 95, 83, 74, 80, 55, 49),3,4)
g1

##      [,1] [,2] [,3] [,4]
## [1,]   67   87   95   80
## [2,]   78   57   83   55
## [3,]   45   98   74   49

cbind(c(22, 34, 43) , g1[  ,3])

##      [,1] [,2]
## [1,]   22   95
## [2,]   34   83
## [3,]   43   74

results <- matrix(c(67,78,45,87,57,98,95,83,74,80,55,49),3,4,byrow=TRUE)
colnames <- c("1st","2nd","3rd","4th")
rownames <- c("car1","car2","car3")
results

##      [,1] [,2] [,3] [,4]
## [1,]   67   78   45   87
## [2,]   57   98   95   83
## [3,]   74   80   55   49

k <- array(1:12,dim=c(2,3,2))
k

## , , 1
## 
##      [,1] [,2] [,3]
## [1,]    1    3    5
## [2,]    2    4    6
## 
## , , 2
## 
##      [,1] [,2] [,3]
## [1,]    7    9   11
## [2,]    8   10   12