List of R Programs

List of Programs for practise of R Programming

1. Write a program to calculate the sum of digits of a given number.
2. Create a function to compute the factorial of a number using both iterative and recursive methods.
3. Implement a program to convert a number from decimal to binary, octal, and hexadecimal.
4. Write a function to count the number of vowels and consonants in a given string.
5. Create a program that reverses a given string without using built-in functions.
6. Write a program to merge two sorted lists into a single sorted list.
7. Create a function to find the largest and smallest numbers in a list.
   
8. Develop a program to count the frequency of each character in a string.
9. Write a program to convert a binary number (as a string) to its decimal equivalent.
10. Create a function to convert temperatures between Celsius, Fahrenheit, and Kelvin.
11. Implement a program to find the sum of even and odd numbers from a list.
12. Develop a program to sort a list of tuples based on the second element in each tuple.
13. Create a program to generate a random password of specified length with letters and digits.
14. Write a function to remove duplicate elements from a list while preserving the order.
15. Implement a program to find common elements between two lists.
16. Create a function to find all prime factors of a given number.
17. Develop a program to find the Greatest Common Divisor (GCD) of two numbers using the Euclidean algorithm.
18. Implement a program to find the n_th largest number in a list.
19. Write a function to remove all whitespace characters from a given string.
20. Implement a program to transpose a given matrix.

R Programs for 20 Problems - Professor Gunupudi

1. Program to calculate the sum of digits of a given number

sum_of_digits <- function(n) {
  digits <- as.numeric(unlist(strsplit(as.character(n), "")))
  return(sum(digits))
}
# Example
sum_of_digits(1234)  # Output: 10

2. Function to compute the factorial using iterative and recursive methods

# Iterative method
factorial_iter <- function(n) {
  result <- 1
  for (i in 1:n) {
    result <- result * i
  }
  return(result)
}

# Recursive method
factorial_rec <- function(n) {
  if (n <= 1) return(1)
  return(n * factorial_rec(n - 1))
}

# Example
factorial_iter(5)  # Output: 120
factorial_rec(5)   # Output: 120

3. Convert a number from decimal to binary, octal, and hexadecimal

convert_number <- function(n) {
  binary <- paste(rev(as.integer(intToBits(n))), collapse = "")
  binary <- sub("^0+", "", binary)
  octal <- as.character(as.octmode(n))
  hex <- toupper(as.character(as.hexmode(n)))
  return(list(Binary = binary, Octal = octal, Hexadecimal = hex))
}

# Example
convert_number(255)

4. Count number of vowels and consonants in a string

count_vowels_consonants <- function(text) {
  text <- tolower(gsub("[^a-z]", "", text))
  chars <- unlist(strsplit(text, ""))
  vowels <- sum(chars %in% c('a', 'e', 'i', 'o', 'u'))
  consonants <- length(chars) - vowels
  return(list(Vowels = vowels, Consonants = consonants))
}

# Example
count_vowels_consonants("Hello World")

5. Reverse a string without using built-in reverse function

reverse_string <- function(s) {
  chars <- strsplit(s, "")[[1]]
  reversed <- chars[length(chars):1]
  return(paste(reversed, collapse = ""))
}

# Example
reverse_string("OpenAI")

6. Merge two sorted lists into a single sorted list

merge_sorted_lists <- function(list1, list2) {
  merged <- sort(c(list1, list2))
  return(merged)
}

# Example
merge_sorted_lists(c(1, 3, 5), c(2, 4, 6))

7. Find the largest and smallest numbers in a list

find_min_max <- function(vec) {
  return(list(Smallest = min(vec), Largest = max(vec)))
}

# Example
find_min_max(c(12, 5, 8, 19, 3))

8. Count the frequency of each character in a string

char_frequency <- function(text) {
  chars <- unlist(strsplit(tolower(gsub("[^a-z]", "", text)), ""))
  return(table(chars))
}

# Example
char_frequency("Hello World")

9. Convert a binary number (string) to its decimal equivalent

binary_to_decimal <- function(bin_str) {
  digits <- as.numeric(strsplit(bin_str, "")[[1]])
  decimal <- sum(digits * 2^((length(digits)-1):0))
  return(decimal)
}

# Example
binary_to_decimal("1101")

10. Convert temperatures between Celsius, Fahrenheit, and Kelvin

convert_temperature <- function(value, from, to) {
  if (from == "C") {
    if (to == "F") return((value * 9/5) + 32)
    if (to == "K") return(value + 273.15)
  } else if (from == "F") {
    if (to == "C") return((value - 32) * 5/9)
    if (to == "K") return((value - 32) * 5/9 + 273.15)
  } else if (from == "K") {
    if (to == "C") return(value - 273.15)
    if (to == "F") return((value - 273.15) * 9/5 + 32)
  }
  return(NA)
}

# Example
convert_temperature(100, "C", "F")

11. Find the sum of even and odd numbers from a list

sum_even_odd <- function(numbers) {
  even_sum <- sum(numbers[numbers %% 2 == 0])
  odd_sum <- sum(numbers[numbers %% 2 != 0])
  return(list(Even_Sum = even_sum, Odd_Sum = odd_sum))
}

# Example
sum_even_odd(c(1, 2, 3, 4, 5, 6))

12. Sort a list of tuples based on the second element

sort_tuples_by_second <- function(tuples) {
  sorted <- tuples[order(sapply(tuples, function(x) x[2]))]
  return(sorted)
}

# Example
list_of_tuples <- list(c("a", 3), c("b", 1), c("c", 2))
sort_tuples_by_second(list_of_tuples)

13. Generate a random password of specified length with letters and digits

generate_password <- function(length) {
  chars <- c(letters, LETTERS, 0:9)
  paste0(sample(chars, length, replace = TRUE), collapse = "")
}

# Example
generate_password(10)

14. Remove duplicate elements from a list while preserving the order

remove_duplicates <- function(vec) {
  unique_vec <- vec[!duplicated(vec)]
  return(unique_vec)
}

# Example
remove_duplicates(c(1, 2, 2, 3, 1, 4))

15. Find common elements between two lists

find_common_elements <- function(list1, list2) {
  return(intersect(list1, list2))
}

# Example
find_common_elements(c(1, 2, 3, 4), c(3, 4, 5, 6))

16. Find all prime factors of a given number

prime_factors <- function(n) {
  factors <- c()
  i <- 2
  while (i <= n) {
    if (n %% i == 0) {
      factors <- c(factors, i)
      n <- n / i
    } else {
      i <- i + 1
    }
  }
  return(factors)
}

# Example
prime_factors(84)

17. Find the Greatest Common Divisor (GCD) using the Euclidean algorithm

gcd <- function(a, b) {
  while (b != 0) {
    temp <- b
    b <- a %% b
    a <- temp
  }
  return(a)
}

# Example
gcd(48, 18)

18. Find the n-th largest number in a list

nth_largest <- function(vec, n) {
  sorted <- sort(unique(vec), decreasing = TRUE)
  if (n <= length(sorted)) {
    return(sorted[n])
  } else {
    return(NA)
  }
}

# Example
nth_largest(c(4, 1, 7, 7, 2, 9), 3)

19. Remove all whitespace characters from a given string

remove_whitespace <- function(text) {
  return(gsub("\\s+", "", text))
}

# Example
remove_whitespace("  Hello   World \n\t")

20. Transpose a given matrix

transpose_matrix <- function(mat) {
  return(t(mat))
}

# Example
m <- matrix(1:6, nrow = 2, ncol = 3)
transpose_matrix(m)