Arithmetic Operators

Operator    Description       Example
-           Subtraction       5 - 1 = 4
+           Addition          5 + 1 = 6
*           Multiplication    5 * 3 = 15
/           Division          10 / 2 = 5
^ or **     Exponentiation    2*2*2*2*2 as 2 to the power of 5
x%%y        Modulus           5%%2 is 1
x%/%y       Integer Division  5%/%2 is 2Relational and Logical Operators

Operator     Description                 Example
<            less than                   5 < 10
<=           less than or equal to       <= 5
>            greater than                10 > 5
>=           greater than or equal to    >= 10
==           exactly equal to            == 10
!=           not equal to                != 5
!x           not x                       x <- c(5), !x
x | y        x or y                      x <- c(5), y <- c(10), x | y
x & y        x and y                     x <- c(5), y <- c(10), x & y
isTRUE(x)    tests whether x is true     x <- TRUE, isTRUE(x)
                                                    [1] FALSE
# Called Logical AND operator. Takes first element of both the vectors and gives the TRUE only if both are TRUE.
v <- c(3,0,TRUE,2+2i)
t <- c(1,3,TRUE,2+3i)
print(v&&t)

# Called Logical OR operator. Takes first element of both the vectors and gives the TRUE if one of them is TRUE.
v <- c(0,0,TRUE,2+2i)
t <- c(0,3,TRUE,2+3i)
print(v||t)

# This operator is used to identify if an element belongs to a vector.

v1 <- 8
v2 <- 12
t <- 1:10
print(v1 %in% t) 
print(v2 %in% t)

num1=10
num2=20
 
if(num1<=num2){
print("Num1 is less or equal to Num2")
    }

x <- 1:15
if (sample(x, 1) <= 10) {
    print("x is less than 10")
} else {
    print("x is greater than 10")
}

x <- 1:15
ifelse(x <= 10, "x less than 10", "x greater than 10")

if (10==10)
    print('10 is equal to 10') else
    print('invalid')

x <- 3
y <- if(x>2){0}else{1}
y

z <- 1:10
ifelse(z<2 | z>8, 1, 0)

ifelse(z>5,'TRUE','FALSE')

z <- 1:10
ifelse(z>4&z>8,"x","?")

x <- c("what","is","truth")

if("Truth" %in% x) {
   print("Truth is found the first time")
} else if ("truth" %in% x) {
   print("truth is found the second time")
} else {
   print("No truth found")
}

vector <- c("aaa","bbb","ccc")
 for(i in vector){   
   print(i)   
}    

for (year in c(2010,2011,2012,2013,2014,2015)){
  print(paste("The year is", year))
}

for(i in 2:5){
    z <- i +1
    print(z)
}

x <- c('a', 'b', 'c', 'd')
for (i in seq_along(x)){
    print(x[i])
}

#alternatively
for (words in x){
    print(words)
}

mymat <- matrix(1:9,3,3)
mymat

for (i in seq_len(nrow(mymat))){
    for (j in seq_len(ncol(mymat))){
        print(mymat[i,j])
    }
}

x <- head(women,10)
x
mrnull <- NULL
for(i in seq_along(x[,1])){
    concat <- c(mrnull, mean(as.numeric(x[i, 1:2])))
    print(concat)
}


# Create your three-dimensional array
my_array <- array(1:20, dim=c(20, 20, 20))

for (i in 1:dim(my_array)[1]) {
  for (j in 1:dim(my_array)[2]) {
    for (k in 1:dim(my_array)[3]) {
      my_array[i,j,k] = i*j*k
    }
  }
}

# Show a 10x10x15 chunk of your array
print(my_array[1:10, 1:10, 1:15])

i <- 1

while (i < 6) {
   print(i)
   i = i+1
}

a <- 0
b <- 1
print(a)
while (b < 50) {
    print(b)
    temp <- a + b
    a <- b
    b <- temp
}

a <- 0
b <- 1
print(a)
while (b < 50) {
     print(b)
     temp <- a + b
     a <- b
     b <- temp
}

x <- 1

repeat {
   print(x)
   x = x+1
   if (x == 6){
       break
   }
}

x <- 1:5

for (val in x) {
    if (val == 3){
        break
    }
    print(val)
}

x <- 1:10
for (num in x){
    if (num==6) break
    mynum <- paste(num, "and so on. ", sep = " ")
    print(mynum)
}

x <- 1:5

for (val in x) {
    if (val == 3){
        next
    }
    print(val)
}

m=20
odd=numeric()

for (k in 1:m) {
   if (!k %% 2)
      next
      odd <- c(odd,k)
}
odd

for (i in 1:10) {
  if (!i %% 2){
    next
  }
    print(i)
}

x <- 1:10
for (num in x){
    if (num %% 3 == 1) next
    mynum <- paste(num, "and so on. ", sep = " ")
    print(mynum)
}

switch(2,"red","green","blue")
# [1] "green"
switch(1,"red","green","blue")
# [1] "red"
################
x <- "red"
switch(x, red="cloth", size=5, name="table")
#################
# If the numeric value is out of range (greater than the number of items in the list or smaller than 1), then, 
# NULL is returned.
 x <- switch(4,"red","green","blue")
 x
 x <- switch(0,"red","green","blue")
 x

number1 <- 30
number2 <- 20
operator <- readline(prompt="Please enter any ARITHMETIC OPERATOR You wish!: ")
 
switch(operator,
       "+" = print(paste("Addition of two numbers is: ", number1 + number2)),
       "-" = print(paste("Subtraction of two numbers is: ", number1 - number2)),
       "*" = print(paste("Multiplication of two numbers is: ", number1 * number2)),
       "^" = print(paste("Exponent of two numbers is: ", number1 ^ number2)),
       "/" = print(paste("Division of two numbers is: ", number1 / number2)),
       "%/%" = print(paste("Integer Division of two numbers is: ", number1 %/% number2)),
       "%%" = print(paste("Division of two numbers is: ", number1 %% number2))
)

# let us take a vector 
vect <- c(1,2,3,4,5,6,7,9)
# now we multiply each element of vect with 5
print(vect * 5)
# now we add each element of vect with 5
print(vect + 5)
# now we subtract each element of vect with 5
print(vect - 5)

For example, to add pairs of numbers contained in two vectors

first <- c(86, 42, 123, -45)
second <- c(78, 210, 48, 52)
first * 5 # with scalar
second / 2.3
first + second # vector with another vector
first * second
first - second
first/second

a <- 1:10
b <- 1:10

res <- numeric(length = length(a))
for (i in seq_along(a)) {
  res[i] <- a[i] + b[i]
}
res

res2 <- a + b
res2
all.equal(res, res2)

a <- 1:10
b <- 1:5
a + b

a <- 1:10
b <- 5
a * b # here b  is a vector of length 1 

a <- 1:10
b <- 1:7
a + b

df <- data.frame(x = 1:3, y = c("a", "b", "c"))
df
df1 <- cbind(df, 1) 
print(df1)