exercise.R

# Exercise 4: DPLYR and flights data

# Install the nycflights13 package and read it in.  Require the dplyr package
# install.packages("nycflights13")
library(nycflights13)
library(dplyr)

# The data.frame flights should now be accessible to you.  View it, 
# and get some basic information about the number of rows/columns


# Add a column that is the amount of time gained in the air (`arr_delay` - `dep_delay`)


# Sort your data.frame desceding by the column you just created


# Try doing the last 2 steps in a single operation using the pipe operator


# Make a histogram of the amount of gain using the `hist` command


# On average, did flights gain or lose time?


# Create a data.frame that is of flights headed to seatac ('SEA'), 


# On average, did flights to seatac gain or loose time?

### Bonus ###
# Write a function that allows you to specify an origin, a destination, and a column of interest
# that returns a data.frame of flights from the origin to the destination and only the column of interest
## Hint: see slides on standard evaluation


# Retireve the air_time column for flights from JFK to SEA


# What was the average air time of those flights (in hours)?  


# What was the min/max average air time for the JFK to SEA flights?