The following question is about wrangling data. Here is the table flights from the nycflights13 package that we have wrangled previously in class.

glimpse(flights)

## Rows: 336,776
## Columns: 19
## $ year           <int> 2013, 2013, 2013, 2013, 2013, 2013, 2013, 2013, 2013,…
## $ month          <int> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,…
## $ day            <int> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,…
## $ dep_time       <int> 517, 533, 542, 544, 554, 554, 555, 557, 557, 558, 558…
## $ sched_dep_time <int> 515, 529, 540, 545, 600, 558, 600, 600, 600, 600, 600…
## $ dep_delay      <dbl> 2, 4, 2, -1, -6, -4, -5, -3, -3, -2, -2, -2, -2, -2, …
## $ arr_time       <int> 830, 850, 923, 1004, 812, 740, 913, 709, 838, 753, 84…
## $ sched_arr_time <int> 819, 830, 850, 1022, 837, 728, 854, 723, 846, 745, 85…
## $ arr_delay      <dbl> 11, 20, 33, -18, -25, 12, 19, -14, -8, 8, -2, -3, 7, …
## $ carrier        <chr> "UA", "UA", "AA", "B6", "DL", "UA", "B6", "EV", "B6",…
## $ flight         <int> 1545, 1714, 1141, 725, 461, 1696, 507, 5708, 79, 301,…
## $ tailnum        <chr> "N14228", "N24211", "N619AA", "N804JB", "N668DN", "N3…
## $ origin         <chr> "EWR", "LGA", "JFK", "JFK", "LGA", "EWR", "EWR", "LGA…
## $ dest           <chr> "IAH", "IAH", "MIA", "BQN", "ATL", "ORD", "FLL", "IAD…
## $ air_time       <dbl> 227, 227, 160, 183, 116, 150, 158, 53, 140, 138, 149,…
## $ distance       <dbl> 1400, 1416, 1089, 1576, 762, 719, 1065, 229, 944, 733…
## $ hour           <dbl> 5, 5, 5, 5, 6, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 6, 6,…
## $ minute         <dbl> 15, 29, 40, 45, 0, 58, 0, 0, 0, 0, 0, 0, 0, 0, 0, 59,…
## $ time_hour      <dttm> 2013-01-01 05:00:00, 2013-01-01 05:00:00, 2013-01-01…

For the following questions, write down the verbs and columns that you would need to use to do the calculations to answer it from the flights table. We provide the code structure and a list of possible verbs for you to select from:

What hour of day should you plan to fly if you want to avoid arrival delays as much as possible?

flights %>% 
  # step 1
  ___(hour) %>%
  # step 2
  ___(avg_delay = mean(___, na.rm = TRUE)) %>% 
  # step 3
  ___(avg_delay)

1. The verb for the first step is group_by()

   The verb for the first step is mutate()

   The verb for the first step is count()
2. The verb for the second step is mutate()

   The verb for the second step is summarise()
3. The appropriate column to compute the mean from is arr_delay

   The appropriate column to compute the mean from is dep_delay
4. The verb for the third step is sort()

   The verb for the third step is arrange()