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Exercise 1: Random numbers and conditions

Let's use runif() again to generate three random numbers between 1 and 100. Store the results to three variables called A, B and C

A  <- runif(min=1, max=100, n=1)
B  <- runif(min=1, max=100, n=1)
C  <- runif(min=1, max=100, n=1)

Now, write a script that checks if A is greater than B and prints a message to the console announcing that A is the greater number.

Answers 
if(A >= B){

    print('A is the greater number')

}

Exercise 2

Extend the script you just write to add another conditional statement. Now, If A is not greater than B, print a message announcing it.

Answers 
if(A >= B){

    print('A is the greater number')

}else{
    print('A is not the greater number')
}

Exercise 3: Our first WHILE loop

Create a variable called start_point and set it to 0. Then, write a WHILE loop that checks if start_point is equal or greater than 60. If start_point value is lower, increase it. Print the value of start_point in each iteration.

Answer 
start_point <- 0

while(start_point <= 60){

    print(paste('start_point value is:', start_point))

    start_point = start_point + 3

}

Exercise 4

Taking the previous answer as a baseline, add the following functionality:

  1. Print start_point value ONLY if its an uneven number.
  2. Add a print message if start_point value is divisible by 5.
Answer 
start_point <- 0

while(start_point <= 60){

    if(start_point %% 2 != 0){
        print(paste('start_point value is:', start_point))
    }else if(start_point %% 5 == 0){
        print(paste(start_point, ' is divisible by 5'))
    }

    start_point = start_point + 3

}

Exercise 5: Calculate the power of fifth

Write a function that takes one argument, called number and returns its fifth power. Call the function get_fifth_power. Use it to calculate the fifth power of 76.

Answer 
get_fifth_power <- function(number){

    power_of_number <- number^5
    return(power_of_number)
}

fifth_power_of_76 <- get_fifth_power(76)

Exercise 5: Division by 0

Write a function that takes two arguments, called A and B, and returns the result of dividing A by B. DO NOT ALLOW the function to perform a division by 0. Name the function divide_numbers.

  1. Try it by setting B to any number and also to 0. What kind of value are you getting as a result?
  2. What would happen If we actually divided by 0?
Answer 
divide_numbers <- function(A, B){

    if(B == 0){ ## Check if we are dividing by 0
        stop('You are dividing by zero!')
    }else{
        return(A / B)
    }
}
  1. We would get NULL If we hadn't added the STOP.
  2. R would return "Inf" as a result.

You probably tried to use IF/ELSE to prevent the function from dividing by zero. However, you will soon find out that in that case, you are getting NULL as the result of executing the function.

stop raises an error message instead of returning NULL, thus allowing us to exit the function and tell the user we encountered an error, instead of silently returning NULL.

Exercise 6: Counting words

Read the documentation for nchar(). Then, write a function called get_longest_word. It must accept two arguments, first_word and second_word. Use nchar() to calculate which word has more characters and return the winner. If both words are of equal length, return "TIE".

Answer 
get_longest_word <- function(first_word, second_word){

    char_difference <- nchar(first_word) - nchar(second_word)

    if(char_difference == 0){
        return('TIE')
    }else{
        result <- ifelse(char_difference > 0, first_word,  second_word)

        return(result)
    }
}

First of all, there are multiple valid solutions to this exercise. This answer makes use of ifelse() to avoid writing a full IF/ELSE block. Alternatively, you could check if there is a tie, then write a nested IF/ELSE block to check which of the words is the longest like below:

get_longest_word <- function(first_word, second_word){

   if(nchar(first_word) == nchar(second_word)){
       return('TIE')
   }else{

       if(nchar(first_word) > nchar(second_word)){
           return(first_word)
       }else{
           return(second_word)
       }
   }
}

At this moment, focus on getting the exercises right. Brevity and readability will naturally come to you later on.