Functions in R

 

These exercises are about the functions sections of Introduction to R.

– Create a function which takes one number and returns the square of that number

squareOfNumber <- function(number){
  squareNumber <- number^2
  return(squareNumber)
}

squareOfNumber(3)

## [1] 9

– Create a function which takes two numbers and returns the mean

meanOfNumbers <- function(number,number2){
  meanOfNumbersRes <- mean(c(number,number2))
  return(meanOfNumbersRes)
}

meanOfNumbers(1,3)

## [1] 2

• Create a function which takes two vectors and returns the mean

meanOfVectors <- function(vector,vector2){
  meanOfVectorsRes <- mean(c(vector,vector2))
  return(meanOfVectorsRes)
}

meanOfVectors(1,3)

## [1] 2

• Create a function which takes two numbers and returns the two numbers as a vector and the mean, summary and multiple as a data.frame.

dfAndVecReturn <- function(number,number2){
  input <- c(number,number2)
  df <- data.frame(mean=mean(c(number,number2)),
                   sum=number+number2,
                   multiple=number*number2
                   )
  return(list(input,df))
}

dfAndVecReturn(1,3)

## [[1]]
## [1] 1 3
## 
## [[2]]
##   mean sum multiple
## 1    2   4        3

– Create a function which takes one argument and finds the smallest number whose factorial is greater than that argument.

findSmallestFactorial <- function(x){
    factorialAnswer <- 0
    count <- 0
    while(factorialAnswer <= x){
      count <- count+1
      if(count == 1){
        factorialAnswer <- 1
      }else{
        factorialAnswer <- factorialAnswer * count 
      }
    }
    return(count)
}

findSmallestFactorial(3000)

## [1] 7

findSmallestFactorial(10^100)

## [1] 70

– Add a if and else statement in your function to only calculate factorial code if argument is a numeric.

findSmallestFactorial <- function(x){
  if(!is.numeric(x)){
    message("Please provide a numeric argument!")
  }else{
    factorialAnswer <- 0
    count <- 0
    while(factorialAnswer <= x){
      count <- count+1
      if(count == 1){
        factorialAnswer <- 1
      }else{
        factorialAnswer <- factorialAnswer * count 
      }
    }
    return(count)
  }
}

findSmallestFactorial(3000)

## [1] 7

findSmallestFactorial("Hello")

## Please provide a numeric argument!