STAT360 Project 2

1. User Defined Funtion A

• Condition

1. Takes a vector as the only input,

2. Returns a summary of numeric vector (mean, 5-number summaries, std dev), and

3. Returns a frequency table of a character vector

vecSum <- function(x){
  if (class(x)=="numeric")
  {
    Mean = mean(x)
    Min = min(x)
    Quant1 = quantile(x, 0.25)
    Med = median(x)
    Quant3 = quantile(x, 0.75)
    Max = max(x)
    Sd = sd(x)
    Summary = c(Mean = Mean, Minimum = Min, "1st Quantile" = Quant1, Median = Med, "3rd Quantile" = Quant3, Maximum = Max, "Standard Deviation" = Sd)
    return(Summary)
  }
  else if (class(x)=="character") {
    return(table(x))
  } 
  else {
    print("You must enter a vector")
  }
}

• Test x = c(12, 20, 18, 32, 15, 20) and y = c("M", "M", "F", "F", "M", "M", "M", "F")

x <- c(12, 20, 18, 32, 15, 20)
y <- c("M", "M", "F", "F", "M", "M", "M", "F")

vecSum(x)

##               Mean            Minimum   1st Quantile.25%             Median 
##          19.500000          12.000000          15.750000          19.000000 
##   3rd Quantile.75%            Maximum Standard Deviation 
##          20.000000          32.000000           6.862944

vecSum(y)

## x
## F M 
## 3 5

2. User Defined Function B

1. Takes a character vector as the only input, and

2. Returns a character vector such that each element of it only has the initial letter in uppercase

FirstUp <- function(x){
  if (class(x)=="character")
  {
    x <- tolower(x)
    substr(x, 1, 1) <- toupper(substr(x, 1, 1))
    return(x)
  }
  else {
    print("You must enter a character vector")
  }
}

• Test using row.names(mtcars) dataset in base R

FirstUp(row.names(mtcars))

##  [1] "Mazda rx4"           "Mazda rx4 wag"       "Datsun 710"         
##  [4] "Hornet 4 drive"      "Hornet sportabout"   "Valiant"            
##  [7] "Duster 360"          "Merc 240d"           "Merc 230"           
## [10] "Merc 280"            "Merc 280c"           "Merc 450se"         
## [13] "Merc 450sl"          "Merc 450slc"         "Cadillac fleetwood" 
## [16] "Lincoln continental" "Chrysler imperial"   "Fiat 128"           
## [19] "Honda civic"         "Toyota corolla"      "Toyota corona"      
## [22] "Dodge challenger"    "Amc javelin"         "Camaro z28"         
## [25] "Pontiac firebird"    "Fiat x1-9"           "Porsche 914-2"      
## [28] "Lotus europa"        "Ford pantera l"      "Ferrari dino"       
## [31] "Maserati bora"       "Volvo 142e"