Learn R with Real Code Examples

count <- 0
isDark <- FALSE

updateUI <- function() {
    cat(paste0('Counter: ', count, '\n'))
    cat(paste0('Theme: ', ifelse(isDark, 'Dark', 'Light'), '\n'))
}

increment <- function() { count <<- count + 1; updateUI() }
decrement <- function() { count <<- count - 1; updateUI() }
reset <- function() { count <<- 0; updateUI() }
toggleTheme <- function() { isDark <<- !isDark; updateUI() }

# Simulate some actions
updateUI()
increment()
increment()
toggleTheme()
decrement()
reset()

Demonstrates a simple counter with theme toggling using R variables and console output.

set.seed(123)
for (i in 1:3) {
    num <- sample(1:100, 1)
    cat(paste0('Random ', i, ': ', num, '\n'))
}

Generates random numbers between 1 and 100 and prints them.

todos <- c()

addTask <- function(task) { todos <<- c(todos, task); print(todos) }
removeTask <- function(index) { todos <<- todos[-index]; print(todos) }

# Simulate actions
addTask('Buy milk')
addTask('Write R code')
removeTask(1)

Maintains a simple todo list with add and remove functionality.

set.seed(42)
for (i in 1:3) {
    roll <- sample(1:6, 1)
    cat(paste0('Roll ', i, ': ', roll, '\n'))
}

Rolls a six-sided dice three times.

count <- 5
while(count >= 0) {
    cat(paste0('Countdown: ', count, '\n'))
    count <- count - 1
}
cat('Done!\n')

Counts down from 5 to 0.

isPrime <- function(n) {
    if(n < 2) return(FALSE)
    for(i in 2:floor(sqrt(n))) {
        if(n %% i == 0) return(FALSE)
    }
    return(TRUE)
}

nums <- c(7, 10, 13)
for(n in nums) {
    cat(paste0(n, ' is ', ifelse(isPrime(n), 'Prime', 'Not Prime'), '\n'))
}

Checks if numbers are prime.

cToF <- function(c) { c * 9/5 + 32 }
fToC <- function(f) { (f - 32) * 5/9 }
cat('25°C =', cToF(25), '°F\n')
cat('77°F =', fToC(77), '°C\n')

Converts Celsius to Fahrenheit and Fahrenheit to Celsius.

cart <- data.frame(Item=character(), Price=numeric())
addItem <- function(item, price) { cart <<- rbind(cart, data.frame(Item=item, Price=price)); print(cart) }
removeItem <- function(index) { cart <<- cart[-index,]; print(cart) }

# Simulate actions
addItem('Apple', 2)
addItem('Banana', 3)
removeItem(1)

Adds and removes items in a shopping cart with total cost.

greet <- function(name) { cat(paste0('Hello, ', name, '! Welcome!\n')) }

# Simulate actions
greet('Saurav')
greet('Alice')
greet('Bob')

Greets users by name.

time <- 0
while(time < 5) {
    cat(paste0('Stopwatch: ', time, ' seconds\n'))
    time <- time + 1
}
cat('Done!\n')

Simulates a stopwatch incrementing seconds.