cat-1.knit

1 numeric integer complex character logical

(v1 <- 8)

## [1] 8

(v2 <- 12)

## [1] 12

(t <- 1:10)

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

print(v1%in%t)

## [1] TRUE

print(v2%%t)

##  [1] 0 0 0 0 2 0 5 4 3 2

v <- c(2,5.5,6)
t <- c(8,3,4)
print(v/t)

## [1] 0.250000 1.833333 1.500000

print(v%%t)

## [1] 2.0 2.5 2.0

print(v%/%t)

## [1] 0 1 1

print(v^t)

## [1]  256.000  166.375 1296.000

print(v<=t)

## [1]  TRUE FALSE FALSE

print(v!=t)

## [1] TRUE TRUE TRUE

(list1 <- list(c(2,5,4),21.3,c("abc","wxz")))

## [[1]]
## [1] 2 5 4
## 
## [[2]]
## [1] 21.3
## 
## [[3]]
## [1] "abc" "wxz"

(x <- c(7,12,9,15,NA,8,14,NA,2,9,8))

##  [1]  7 12  9 15 NA  8 14 NA  2  9  8

y <- x[!is.na(x)]
length(y)

## [1] 9

y[y>10]

## [1] 12 15 14

(v <- seq(16,26,2))

## [1] 16 18 20 22 24 26

length(v)

## [1] 6

sum(v)

## [1] 126

v[1:4]

## [1] 16 18 20 22

v[2:5]

## [1] 18 20 22 24

v[c(2,4,6)]

## [1] 18 22 26

v[v>20]

## [1] 22 24 26

v[3]

## [1] 20

print(w <- v*3)

## [1] 48 54 60 66 72 78

length(w[w<60])

## [1] 2

(m <- matrix(3:14,ncol = 3))

##      [,1] [,2] [,3]
## [1,]    3    7   11
## [2,]    4    8   12
## [3,]    5    9   13
## [4,]    6   10   14

m+m

##      [,1] [,2] [,3]
## [1,]    6   14   22
## [2,]    8   16   24
## [3,]   10   18   26
## [4,]   12   20   28

3*m

##      [,1] [,2] [,3]
## [1,]    9   21   33
## [2,]   12   24   36
## [3,]   15   27   39
## [4,]   18   30   42

m[1,1]

## [1] 3

#matrix transpose ie t() exchanges the position of the columns and rows in a matrix
t(m)

##      [,1] [,2] [,3] [,4]
## [1,]    3    4    5    6
## [2,]    7    8    9   10
## [3,]   11   12   13   14

m[1,1:2]

## [1] 3 7

m[1:2,]

##      [,1] [,2] [,3]
## [1,]    3    7   11
## [2,]    4    8   12

m[2:3,c(2,3)]

##      [,1] [,2]
## [1,]    8   12
## [2,]    9   13

#in the code below,ignore the middle part ie " <- m[,2]" and only consider the part "m <- 0"
m <- m[,2] <- 0
m

## [1] 0

factors

(sex <- sample(1:2,40,replace = T))

##  [1] 1 2 2 2 2 1 2 1 2 1 2 1 1 1 1 2 2 2 1 1 2 1 1 1 2 1 1 2 1 2 1 2 1 1 1 1 1 2
## [39] 2 1

(sex.1 <- paste(sex,collapse = ","))

## [1] "1,2,2,2,2,1,2,1,2,1,2,1,1,1,1,2,2,2,1,1,2,1,1,1,2,1,1,2,1,2,1,2,1,1,1,1,1,2,2,1"

(sex.2 <- factor(sex))

##  [1] 1 2 2 2 2 1 2 1 2 1 2 1 1 1 1 2 2 2 1 1 2 1 1 1 2 1 1 2 1 2 1 2 1 1 1 1 1 2
## [39] 2 1
## Levels: 1 2

(levels(sex.2) <- c("females","males"))

## [1] "females" "males"

sex.2

##  [1] females males   males   males   males   females males   females males  
## [10] females males   females females females females males   males   males  
## [19] females females males   females females females males   females females
## [28] males   females males   females males   females females females females
## [37] females males   males   females
## Levels: females males

list(sex.2)

## [[1]]
##  [1] females males   males   males   males   females males   females males  
## [10] females males   females females females females males   males   males  
## [19] females females males   females females females males   females females
## [28] males   females males   females males   females females females females
## [37] females males   males   females
## Levels: females males

levels(sex.2)[levels(sex.2)=="males"] <- "me"
levels(sex.2)[levels(sex.2)=="females"] <- "you"
sex.2

##  [1] you me  me  me  me  you me  you me  you me  you you you you me  me  me  you
## [20] you me  you you you me  you you me  you me  you me  you you you you you me 
## [39] me  you
## Levels: you me

TIME

as.POSIXct("2004-06-11 16:00:00")

## [1] "2004-06-11 16:00:00 EAT"

strptime("04/06/11","%y/%m/%d")

## [1] "2004-06-11 EAT"

format(strptime("04/06/11","%y/%m/%d"),"%a %b %d %Y")

## [1] "Fri Jun 11 2004"

strptime("04/06/11","%y/%m/%d")-strptime("05/03/18","%y/%m/%d")

## Time difference of -280 days

data<-sample(1:3,50,replace = T)
data<-factor(data)
levels(data)<-c("Nakuru","nairobi","Eldoret")
data

##  [1] Eldoret nairobi nairobi nairobi Nakuru  nairobi nairobi nairobi Nakuru 
## [10] Nakuru  Eldoret nairobi Nakuru  nairobi Nakuru  Nakuru  Eldoret Eldoret
## [19] Eldoret Nakuru  Nakuru  nairobi Nakuru  Nakuru  Nakuru  nairobi Eldoret
## [28] Eldoret Nakuru  nairobi Eldoret Nakuru  nairobi nairobi Nakuru  Eldoret
## [37] Eldoret Nakuru  Nakuru  Nakuru  Eldoret Eldoret nairobi Eldoret Eldoret
## [46] Nakuru  nairobi Nakuru  Eldoret Eldoret
## Levels: Nakuru nairobi Eldoret