1. How to Write an R Code (Syntax and Print)
R uses simple syntax to execute commands. Code is written line-by-line, and print() or cat() displays output. Try, if you can solve the below problem.
# HW 1: Print "Hello, R!"
# HW 2: Calculate 5 + 3 and print the result print("Hello, R!")
cat("Result:", 5 + 3) 2. To See a Data Type
Use class() / typeof() to check the data type of a variable (e.g., numeric, character).
# HW 1: Check the type of "apple"
# HW 2: Check the type of 25.6 class("apple") # Output: "character"
typeof(25.6) # Output: "double" 3. To Set a Data Type
Use as. function to set forcefully a data type like as.numeric() or as.character().
# HW 1: Convert "100" to numeric
# HW 2: Convert 50 to character as.numeric("100") # Output: 100
as.character(50) # Output: "50" 4. To Handle Multiple values at once
Use vectors (created with c()) to store multiple values of the same type.
# HW 1: Create a vector of numbers 1, 2, 3
# HW 2: Create a vector of colors: "red", "blue" nums <- c(1, 2, 3)
colors <- c("red", "blue") 5. To Define a Value
Assign values to variables using <- or =. Example: x <- 10.
# HW 1: Assign 3.14 to "pi"
# HW 2: Assign "Rocks" to "language" pi <- 3.14
language <- "Rocks" 6. How to make a Comment
Use # to add comments (notes) to your code. R ignores these lines.
# HW 1: Write a comment explaining the next line
print("Learning R!") # This line prints a motivational message
print("Learning R!") 7. Variables and Their Types
Variables in R store data, and their type is automatically inferred from the assigned value. Use <- or = to assign values. Example: x <- 10 (numeric), y <- "Hello" (character).
# HW1: Assign 3.14 to a variable
# HW2: Assign "R Programming" to a variable
# HW3: Assign TRUE to a variable pi_value <- 3.14
language <- "R Programming"
is_fun <- TRUE 8. Different Data Types in R
R supports numeric (e.g., 10.5), integer (e.g., 55L), complex (e.g., 9+3i), character (e.g., "R is exciting"), and logical (e.g., TRUE). Use class() to check the type.
# HW1: Create a numeric variable with 787
# HW2: Create an integer with 100L
# HW3: Create a complex number 9+3i
# HW4: Create a character "FALSE"
# HW5: Create a logical FALSE num <- 787
integer_val <- 100L
complex_num <- 9 + 3i
char <- "FALSE"
logical_val <- FALSE 9. Simple Math Functions
R has built-in functions for math operations:
min(): Finds the smallest value.
floor(): Rounds down to the nearest integer.
max(): Finds the largest value.
sqrt(): Calculates the square root.
abs(): Returns absolute value.
ceiling(): Rounds up to the nearest integer.
# HW1: Find the minimum of 10, 20, 5
# HW2: Calculate the square root of 16
# HW3: Round 3.2 up and 4.9 down
# HW4: Get the absolute value of -7.5 min_val <- min(10, 20, 5) # Output: 5
sqrt_val <- sqrt(16) # Output: 4
ceil_val <- ceiling(3.2) # Output: 4
floor_val <- floor(4.9) # Output: 4
abs_val <- abs(-7.5) # Output: 7.5 10. Boolean’s (Logical Values)
Booleans are TRUE or FALSE. Use logical operators like & (AND), | (OR), and ! (NOT) to combine conditions.
# HW1: Check if 5 > 3 AND 2 < 4
# HW2: Check if 10 == 10 OR 7 != 7
# HW3: Reverse the value of TRUE bool1 <- (5 > 3) & (2 < 4)
bool1 # Output: TRUE
bool2 <- (10 == 10) | (7 != 7)
bool2 # Output: TRUE
bool3 <- !TRUE
bool3 # Output: FALSE
11. Arithmetic Operators
Used for basic math operations: + (add), - (subtract), * (multiply), / (divide), ^ (exponent), %% (modulus).
# HW1: Calculate 10 + 5
# HW2: Calculate 10 - 5
# HW3: Calculate 4 * 6
# HW4: Calculate 20 / 4
# HW5: Calculate 3^2 (3 squared)
# HW6: Find the remainder of 10 %% 3 add <- 10 + 5 # 15
sub <- 10 - 5 # 5
mul <- 4 * 6 # 24
div <- 20 / 4 # 5
exp <- 3^2 # 9
mod <- 10 %% 3 # 1 12. Assignment Operators
Assign values to variables: <-, =, or -> (rarely used). Example: x <- 5 or 5 -> x.
# HW1: Assign 10 to `a` using `<-`
# HW2: Assign 20 to `b` using `=`
# HW3: Assign 30 to `c` using `->` a <- 10
b = 20
30 -> c 13. Comparison Operators
Compare values: == (equal), != (not equal), >, <, >=, <=. Returns TRUE or FALSE.
# HW1: Check if 5 == 5
# HW2: Check if 10 != 5
# HW3: Check if 8 > 3
# HW4: Check if 4 <= 4 5 == 5 # TRUE
10 != 5 # TRUE
8 > 3 # TRUE
4 <= 4 # TRUE 14. Logical Operators
Combine conditions: & (AND), | (OR), ! (NOT).
# HW1: Check if (5 > 3) & (2 < 4)
# HW2: Check if (10 == 5) | (3 != 3)
# HW3: Reverse the result of TRUE using `!` (5 > 3) & (2 < 4) # TRUE
(10 == 5) | (3 != 3) # FALSE
not_op <- !TRUE
not_op # FALSE 15. If-Else Statements
Use if to execute code if a condition is TRUE, and else for when it’s FALSE.
# HW1: Check if 10 is greater than 5, print "Yes"
# HW2: Check if 7 is even; if not, print "Odd"
# HW3: Assign "Pass" if score >= 50, else "Fail" # HW1
if (10 > 5) {
print("Yes")
}
# HW2
if (7 %% 2 == 0) {
print("Even")
} else {
print("Odd")
}
# HW3
score <- 55
result <- if (score >= 50) "Pass" else "Fail"
print(result) 16. While Loop
Repeats code while a condition is TRUE. Use break to exit early.
# HW1: Print numbers 1 to 5
# HW2: Sum numbers from 1 to 3 # HW1
i <- 1
while (i <= 5) {
print(i)
i <- i + 1
}
# HW2
total <- 0
j <- 1
while (j <= 3) {
total <- total + j
j <- j + 1
}
print(total) # Output: 6 17. For Loop
Iterates over a sequence (like a vector). Use break/next to control flow.
# HW1: Print numbers 1 to 3 from c(1, 2, 3)
# HW2: Calculate sum of 1, 2, 3 using a loop
# HW3: Loop through a matrix (2x2) and print values # HW1
for (num in c(1, 2, 3)) {
print(num)
}
# HW2
sum <- 0
for (i in 1:3) {
sum <- sum + i
}
print(sum) # Output: 6
# HW3
mat <- matrix(1:4, nrow=2)
for (row in 1:nrow(mat)) {
for (col in 1:ncol(mat)) {
print(mat[row, col])
}
} 18. Functions
Reusable code blocks. Use function() to define, and return() to output results.
# HW1: Create a function to square a number
# HW2: Create a function that says "Hello, [name]!" # HW1
square <- function(x) {
return(x^2)
}
print(square(4)) # Output: 16
# HW2
greet <- function(name) {
return(paste("Hello,", name, "!"))
}
print(greet("Alice")) # Output: "Hello, Alice!"