HW 5

Functions

1- Create a function named calculate_area_of_circle that takes one parameter, radius, representing the radius of a circle. The function should calculate and return the area using the formula:

area = 𝜋 × radius^2

Test your function with at least two different radii and print the results.

calculate_area_of_circle <- function(radius){
  area <- 3.14 * radius^2
  return(area)
}
  
area_test_one <- calculate_area_of_circle(5)

print(area_test_one)

## [1] 78.5

area_test_two <- calculate_area_of_circle(10)

print(area_test_two)

## [1] 314

2- Write a function called check_temperature that takes a single numeric input temp.

If temp > 30, print “Hot”

If temp >= 15 & temp <= 30, print “Warm”

Otherwise, print “Cold”

Test the function on three different values (e.g., 10, 20, 35).

check_temperature <- function(temp_input){
  if (temp_input > 30){
     print('Hot')
  }
   else if (temp_input >= 15 & temp_input <=30){
     print('Warm')
   }
  else {
    print('Cold')
  }
    
}

check_temp_test_one <- check_temperature(10)

## [1] "Cold"

check_temp_test_two <- check_temperature(20)

## [1] "Warm"

check_temp_test_three <- check_temperature(35)

## [1] "Hot"

cat('Test one prints:',check_temp_test_one,"\n",
    'Test two prints:',check_temp_test_two,"\n",
    'Test three prints:',check_temp_test_three,"\n")

## Test one prints: Cold 
##  Test two prints: Warm 
##  Test three prints: Hot

3- Write a function named sum_odd_numbers that uses a for loop to calculate the sum of all even numbers from 1 to n. The function should return the total sum.

Test the function with n = 9 and n = 39.

#Calculates the sum of all even numbers, from 1 through the input, n
sum_odd_number <- function(n){
  total=0
  for (i in 1:n){
    if (i %% 2 == 0){
      total = total + i
     }
    
  }
  return(total)
}

sum_odd_number(9)

## [1] 20

sum_odd_number(39)

## [1] 380

EDA

For this section, use the built-in mtcars dataset (instead of airquality). Perform the following:

• Check the structure of the dataset.

• Display the summary statistics.

• Check for any missing values.

Ask a simple question that can be answered with a basic function (e.g., What is the mean miles per gallon (mpg) across all cars?). Write the code and output the answer.

#mtcars
#str(mtcars)
#summary(mtcars)
#is.na(mtcars)

#What is the mean hp across all cars? 
mtcars_hp_finder <- function(){
  return(mean(mtcars$hp))
}

mtcars_hp_finder()

## [1] 146.6875

cat('The average horsepower across all vehicles in the mtcars dataset is:', mtcars_hp_finder())

## The average horsepower across all vehicles in the mtcars dataset is: 146.6875