Conditional Statements Exercises - Solutions

For these exercises, use what you have learned about if,else if, and else statements to answer the questions! The first exercise is done for you as an example:

Example: Write a script that prints "Hello" if the variable x is equal to 1:

x <- 1

if (x ==1){
    print("Hello")
}

[1] "Hello"

Exercise Problems

Ex 1: Write a script that will print "Even Number" if the variable x is an even number, otherwise print "Not Even":

x <- 3 # Change x to test

if (x%%2 == 0){
    print('Even Number')
}else{
    print('Not Even')
}

[1] "Not Even"

Ex 2: Write a script that will print 'Is a Matrix' if the variable x is a matrix, otherwise print "Not a Matrix". Hint: You may want to check out help(is.matrix)

x <- matrix()

if (is.matrix(x)){
    print('Is a Matrix')
}else{
    print("Not a Matrix")
}

[1] "Is a Matrix"

Ex 3: Create a script that given a numeric vector x with a length 3, will print out the elements in order from high to low. You must use if,else if, and else statements for your logic. (This code will be relatively long)

x <- c(3,7,1)

if (x[1] > x[2]){
    fir <- x[1]
    sec <- x[2]
} else {
    fir <- x[2]
    sec <- x[1]
}
if ( x[3] > fir & x[3] > sec ) {
    thi <- sec
    sec <- fir
    fir <- x[3]
} else if ( x[3] < fir & x[3] < sec ) {
    thi <- x[3]
} else {
    thi <- sec
    sec <- x[3]
}

print(paste(fir, sec, thi))

[1] "7 3 1"

Ex 4: Write a script that uses if,else if, and else statements to print the max element in a numeric vector with 3 elements.

x <- c(20, 10, 1)

if (x[1] > x[2] & x[1] > x[3] ) {
    print(x[1] )
} else if (x[2] > x[3] ) {
    print(x[2])
} else {
    print(x[3])
}

[1] 20

Great Job!