ch_18_solutions

Prerequisites:

---

library(tidyverse)
library(nycflights13)

18.3.4 Exercises:

1. Whether a flight has the tail number recorded in planes is highly correlated with the carrier, with nearly all flights from MQ (Envoy Air) not having a tail number recorded. Interesting to note that Envoy Air is a subsidiary of AA, the other carrier with a high proportion of tail numbers missing.

   tailnum_not_in_plane <- flights |> 
     distinct(tailnum) |> 
     anti_join(planes, by = 'tailnum') |> 
     pull()
   
   flights |> 
     group_by(carrier) |> 
     summarise(
       number_of_flights = n(),
       no_tail = sum(tailnum %in% tailnum_not_in_plane),
       perc_no_tail = round(no_tail / (number_of_flights) *100, 2)
     ) |> 
     arrange(desc(number_of_flights))
   ## # A tibble: 16 × 4
   ##    carrier number_of_flights no_tail perc_no_tail
   ##    <chr>               <int>   <int>        <dbl>
   ##  1 UA                  58665    1693         2.89
   ##  2 B6                  54635     830         1.52
   ##  3 EV                  54173       0         0   
   ##  4 DL                  48110     110         0.23
   ##  5 AA                  32729   22558        68.9 
   ##  6 MQ                  26397   25397        96.2 
   ##  7 US                  20536     699         3.4 
   ##  8 9E                  18460    1044         5.66
   ##  9 WN                  12275      38         0.31
   ## 10 VX                   5162       0         0   
   ## 11 FL                   3260     187         5.74
   ## 12 AS                    714       0         0   
   ## 13 F9                    685      50         7.3 
   ## 14 YV                    601       0         0   
   ## 15 HA                    342       0         0   
   ## 16 OO                     32       0         0