by: babak babaabasi

R If … Else

Conditions and If Statements

x = readline(prompt="Enter an integer number: ")



if(x>3) print("Positive")
if(x<7) print("negative")

Write the R script that take two integers as input and print out the larger number.

A = as.numeric(readline(prompt="Enter first numbera: "))
B = as.numeric(readline(prompt="Enter second number: "))
if(A > B) print(A)
if(B > A) print(B)

x = as.integer(readline(prompt="Enter an integer number: "))
if(x>0) print("Positive") else print("Negative")

You can also run a condition in an if statement, which you will learn much more about in the if..else chapter.

a = 200
b = 33

if (b > a) {
  print ("b is greater than a")
} else {
  print("b is not greater than a")
}

if (b > a) {
  (b*4)
} else {
  (b*2)
}

A = as.integer(readline(prompt="Enter an integer number: "))
B = as.integer(readline(prompt="Enter an integer threshold: "))
if(A > B){
print(paste(A, "is greater than threshold ", B), quote=F)
} else if (A < B){
print(paste(A, "is less than threshold ", B), quote=F)
} else {
print (paste(A, "is equal to threshold ", B), quote=F)
}

a <- 200
b <- 33

if (b > a) {
  print("b is greater than a")
} else if (a == b) {
  print("a and b are equal")
} else {
  print("a is greater than b")
}

Nested If Statements

x <- 44

if (x > 10) {
  print("Above ten")
  if (x > 20) {
    print("and also above 20!")
  } else {
    print("but not above 20.")
  }
} else {
  print("below 10.")
}

AND

The & symbol (and) is a logical operator, and is used to combine conditional statements:

a <- 200
b <- 33
c <- 500

if (a > b & c > a){
  print("Both conditions are true")
}

OR

The | symbol (or) is a logical operator, and is used to combine conditional statements:

a <- 200
b <- 33
c <- 500

if (a > b | a > c){
  print("At least one of the conditions is true")
}

R While Loop

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

a=c(45,67,89,90,56,44,78,34)
i = 1
l=length(a)
f=0
while (i <= l) {
  f=a[i]+f
  i = i+1
  m=f/l
  print(m)
}

# R program to illustrate
# application of while loop
 
# assigning value to the variable
# whose factorial will be calculated
n < - 5
 
# assigning the factorial variable
# and iteration variable to 1
factorial < - 1
i < - 1
 
# using while loop
while (i <= n)
{
 
    # multiplying the factorial variable
    # with the iteration variable
    factorial = factorial * i
 
    # incrementing the iteration variable
    i = i + 1
}
 
# displaying the factorial
print(factorial)


n = 5
factorial = 1
i = 1

while (i <= n){
    factorial = factorial * i
    i = i + 1
}

print(factorial)

R For Loop

for (val in sequence)
{
statement
}

f = c(2,5,3,9,8,11,6,11,12,20)
count = 0
for (val in f) {
if(val %% 2 == 0)  
count = count+1
}
print(count)

factorial by for

num =6
factorial = 1
for(i in 1:num) {
factorial = factorial * i
}
print(paste("The factorial of", num ,"is",factorial))

factorial by for

# take input from the user
num = as.integer(readline(prompt="Enter a number: "))
factorial = 1
# check is the number is negative, positive or zero
if(num < 0) {
print("Sorry, factorial does not exist for negative numbers")
} else if(num == 0) {
print("The factorial of 0 is 1")
} else {
for(i in 1:num) {
factorial = factorial * i
}
print(paste("The factorial of", num ,"is",factorial))
}

break statement

x <- 1:5
for (val in x) {
if (val == 3){
break
}
print(val)
}

Function

my_function <- function() {
  print("Hello World!")
}
my_function() # call the function named my_function =

meanlog=function(x,y){
  b=log(mean(x)+mean(y))
  print(b)
}
a=c(45,67,89,90)
h=c(2,4,55,67,88)
t=c(55,67,99,89)
meanlog(a,t)

novin = function(x,y) {
  paste(x,"hasani",y, "bagheri")
}



novin("zahra","hoseen")

bmi = function(ghad,vazn) {
  x=vazn/(ghad^2)
  print(paste(x,"your bmi"))
}




bmi(1.60,65)

my_function = function(fname, lname) {
  paste(fname, lname)
}

my_function("Peter", "Griffin")

Default Parameter Value

The following example shows how to use a default parameter value.

If we call the function without an argument, it uses the default value:

my_function <- function(country = "Norway") {
  paste("I am from", country)
}

my_function("Sweden")
my_function("India")
my_function() # will get the default value, which is Norway
my_function("USA")

Return Values

To let a function return a result, use the return() function:

my_function <- function(x) {
  return (5 * x)
}

print(my_function(3))
print(my_function(5))
print(my_function(9))

v=c(5,6,8,9,14)
rescale <- function(v) { # Rescales a vector, v, to lie in the range 0 to 1.
L <- min(v)
H <- max(v)
result <- (v - L) / (H - L)
return(result)
}
rescale(v)

sahar=function(n){
  factorial = 1
  i = 1
while (i <= n)
{
    factorial = factorial * i
    i = i + 1
}
print(factorial)
}
sahar(5)

END(1-2)

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