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Mastering Control Structures in R Programming: Learn How to Use If-Else, Switch Case, and For Loops Like a Pro!

The Beginner’s Guide to Control Structures (If-Else, Switch-Case, & For Loops) in R Programming:

Control structures are essential in programming languages as they determine the flow of the program. In R programming, there are several control structures available, including if-else, switch case, and for loops.


If-Else statement:

The if-else statement is used to check the condition and execute a block of code accordingly. The syntax of the if-else statement in R is as follows:

if (condition) { 
                     # Execute code if the condition is true 
                     } 
else { 
        # Execute code if the condition is false 
        }

For example, consider the following code that checks whether a number is even or odd:

num <- 10 
if (num %% 2 == 0) { 
                                 print("The number is even") 
                                 } 
else { 
         print("The number is odd") 
        }

Output:
[1] "The number is even"

Switch case statement:

The switch case statement is used to compare a single value against multiple possible values and execute a block of code accordingly. The syntax of the switch case statement in R is as follows:

switch (expression, 
           value1 = code1, 
           value2 = code2, 
           ..., 
           default = codeN)

For example, consider the following code that checks the day of the week:

day <- "Monday"

switch (day,
        "Monday" = print("Today is Monday"),
        "Tuesday" = print("Today is Tuesday"),
        "Wednesday" = print("Today is Wednesday"),
        "Thursday" = print("Today is Thursday"),
        "Friday" = print("Today is Friday"),
        "Saturday" = print("Today is Saturday"),
        "Sunday" = print("Today is Sunday"),
        print("Invalid day"))

Output:
[1] "Today is Monday"

For loop:

The for loop is used to execute a block of code repeatedly for a specified number of times. The syntax of the for loop in R is as follows:

for (variable in sequence) {
  # Execute code for each value of the variable
}

For example, consider the following code that prints the numbers from 1 to 5:
for (i in 1:5) { 
                    print(i)
                    }

Output:
[1] 1
[1] 2
[1] 3
[1] 4
[1] 5


Practice Material:

Here are a few practice exercises to help you get started:

  • Write a program that takes the temperature as input and prints "It's cold outside" if the temperature is below 10 degrees Celsius, "It's warm outside" if the temperature is between 10 and 25 degrees Celsius, and "It's hot outside" if the temperature is above 25 degrees Celsius.
  • Write a program that takes the day of the week as input and prints "Weekday" if it's Monday to Friday, "Weekend" if it's Saturday or Sunday, and "Invalid day" for any other value.
  • Write a program that calculates the sum of the first 10 natural numbers using a for loop.
  • For more practice you should start swirl's lesson number eight in R Programming. Complete download process of swirl and R Programming is here, click on the link!
  • You can look in to the practice and reading material that is provided in the text book, click here to download the textbook.
  • Lecture slides can be downloaded from here. It would be great if you go through them too.

These practice materials are suitable for you to get hands-on experience with control structures in R programming. Good luck!
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