Writing Functions in R

Examples

Using the 1990 flight data, define a function called `myaveragedelay` that takes a 3-letter string (correspding to an airport code) and finds the average departure delays (after removing the NA values) from the `DepDelay` column. Use `myaveragedelay("IND")` to print the average departure delays for flights with Origin airport "IND".

Click to see solution

flightDF <- read.csv("/anvil/projects/tdm/data/flights/subset/1990.csv")
myaveragedelay = function(x) {mean(flightDF$DepDelay[flightDF$Origin == x], na.rm=TRUE)}

myaveragedelay("IND")

5.96977225672878

Using the 1990 flight data, define a function called `myaveragedelay` that takes a 3-letter string (correspding to an airport code) and finds the average departure delays (after removing the NA values) from the `DepDelay` column. Use `myaveragedelay("JFK")` to print the average departure delays for flights with Origin airport "IND".

Click to see solution

flightDF <- read.csv("/anvil/projects/tdm/data/flights/subset/1990.csv")
myaveragedelay = function(x) {mean(flightDF$DepDelay[flightDF$Origin == x], na.rm=TRUE)}

myaveragedelay("JFK")

 11.8572741063607

Write a function called `monthlydepdelays` that takes a year as the input and returns a table of length 12 with the average DepDelay for flights starting at IND in each of the 12 months of that year.

Click to see solution

monthlydepdelays <- function(year) {
  file_path <- paste0("/anvil/projects/tdm/data/flights/subset/", as.character(year), ".csv")
  flights <- read.csv(file_path)
  ind_flights <- subset(flights, Origin == "IND")
  avg_delays <- tapply(ind_flights$DepDelay, ind_flights$Month, mean, na.rm = TRUE)
  return(avg_delays)
}

monthlydepdelays(1990)

1
    7.28277205677707
2
    9.49702660406886
3
    6.92484111633048
4
    4.94985835694051
5
    5.47148703956344
6
    6.01083547191332
7
    4.30737704918033
8
    5.63978201634877
9
    4.45558583106267
10
    4.47372488408037
11
    3.4083044982699
12
    9.76410531972058