Learn R - 10 Code Examples & CST Typing Practice Test

R is a high-level, interpreted programming language and environment specifically designed for statistical computing, data analysis, and graphical representation. It provides a rich ecosystem of packages and functions for statistical modeling, data visualization, and reproducible research.

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R Counter and Theme Toggle R Random Number Generator R Todo List R Dice Roller R Countdown Timer R Prime Checker R Temperature Converter R Shopping Cart R Name Greeting R Stopwatch

Learn R with Real Code Examples

Updated Nov 21, 2025

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Code Sample Descriptions

R Counter and Theme Toggle

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.

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R Random Number Generator

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.

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R Todo List

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.

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R Dice Roller

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.

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R Countdown Timer

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

Counts down from 5 to 0.

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R Prime Checker

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.

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R Temperature Converter

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.

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R Shopping Cart

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.

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R Name Greeting

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

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

Greets users by name.

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R Stopwatch

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

Simulates a stopwatch incrementing seconds.

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Frequently Asked Questions about R

What is R?

What are the primary use cases for R?

Statistical modeling and hypothesis testing. Data visualization and reporting. Machine learning and predictive analytics. Bioinformatics and genomic data analysis. Financial and econometric analysis

What are the strengths of R?

Excellent for statistical analysis and data visualization. Vast ecosystem of specialized packages. Strong community support for data science. Open-source with extensive documentation. Highly reproducible workflows using R Markdown

What are the limitations of R?

Slower than compiled languages for large datasets. Memory-intensive with very large data. Steeper learning curve for programming beginners. Less suited for general-purpose software development. Graphical performance can lag behind modern GUI frameworks

How can I practice R typing speed?

CodeSpeedTest offers 10+ real R code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Learn R - 10 Code Examples & CST Typing Practice Test

Code Sample Descriptions

R Counter and Theme Toggle

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.

Let’s Try →

R Random Number Generator

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.

Let’s Try →

R Todo List

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.

Let’s Try →

R Dice Roller

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.

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R Countdown Timer

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

Counts down from 5 to 0.

Let’s Try →

R Prime Checker

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.

Let’s Try →

R Temperature Converter

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.

Let’s Try →

R Shopping Cart

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.

Let’s Try →

R Name Greeting

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

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

Greets users by name.

Let’s Try →

R Stopwatch

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

Simulates a stopwatch incrementing seconds.

Let’s Try →

Frequently Asked Questions about R

What is R?

What are the primary use cases for R?

Statistical modeling and hypothesis testing. Data visualization and reporting. Machine learning and predictive analytics. Bioinformatics and genomic data analysis. Financial and econometric analysis

What are the strengths of R?

What are the limitations of R?

How can I practice R typing speed?

CodeSpeedTest offers 10+ real R code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.