#Library
pacman::p_load(dplyr)#Question 1
pacman::p_load(nycflights13)
# Both View and Glimpse gave me error codes when I attempted to knit, but ran in my markdown
# this View() function opens lets you directly view the whole dataset
# this glimpse() function provides a quick overview of the dataset
summary(flights)## year month day dep_time sched_dep_time
## Min. :2013 Min. : 1.000 Min. : 1.00 Min. : 1 Min. : 106
## 1st Qu.:2013 1st Qu.: 4.000 1st Qu.: 8.00 1st Qu.: 907 1st Qu.: 906
## Median :2013 Median : 7.000 Median :16.00 Median :1401 Median :1359
## Mean :2013 Mean : 6.549 Mean :15.71 Mean :1349 Mean :1344
## 3rd Qu.:2013 3rd Qu.:10.000 3rd Qu.:23.00 3rd Qu.:1744 3rd Qu.:1729
## Max. :2013 Max. :12.000 Max. :31.00 Max. :2400 Max. :2359
## NA's :8255
## dep_delay arr_time sched_arr_time arr_delay
## Min. : -43.00 Min. : 1 Min. : 1 Min. : -86.000
## 1st Qu.: -5.00 1st Qu.:1104 1st Qu.:1124 1st Qu.: -17.000
## Median : -2.00 Median :1535 Median :1556 Median : -5.000
## Mean : 12.64 Mean :1502 Mean :1536 Mean : 6.895
## 3rd Qu.: 11.00 3rd Qu.:1940 3rd Qu.:1945 3rd Qu.: 14.000
## Max. :1301.00 Max. :2400 Max. :2359 Max. :1272.000
## NA's :8255 NA's :8713 NA's :9430
## carrier flight tailnum origin
## Length:336776 Min. : 1 Length:336776 Length:336776
## Class :character 1st Qu.: 553 Class :character Class :character
## Mode :character Median :1496 Mode :character Mode :character
## Mean :1972
## 3rd Qu.:3465
## Max. :8500
##
## dest air_time distance hour
## Length:336776 Min. : 20.0 Min. : 17 Min. : 1.00
## Class :character 1st Qu.: 82.0 1st Qu.: 502 1st Qu.: 9.00
## Mode :character Median :129.0 Median : 872 Median :13.00
## Mean :150.7 Mean :1040 Mean :13.18
## 3rd Qu.:192.0 3rd Qu.:1389 3rd Qu.:17.00
## Max. :695.0 Max. :4983 Max. :23.00
## NA's :9430
## minute time_hour
## Min. : 0.00 Min. :2013-01-01 05:00:00
## 1st Qu.: 8.00 1st Qu.:2013-04-04 13:00:00
## Median :29.00 Median :2013-07-03 10:00:00
## Mean :26.23 Mean :2013-07-03 05:22:54
## 3rd Qu.:44.00 3rd Qu.:2013-10-01 07:00:00
## Max. :59.00 Max. :2013-12-31 23:00:00
## #Question 2
#Option A - Correct
maxdep <- max(flights$dep_delay, na.rm=TRUE)
maxdep_id <- which(flights$dep_delay==maxdep)
flights[maxdep_id, 10:12]## # A tibble: 1 × 3
## carrier flight tailnum
## <chr> <int> <chr>
## 1 HA 51 N384HA#Option B - Correct
sortif <- arrange(flights,desc(dep_delay))
select(sortif, carrier, flight, tailnum, everything())## # A tibble: 336,776 × 19
## carrier flight tailnum year month day dep_time sched_dep_time dep_delay
## <chr> <int> <chr> <int> <int> <int> <int> <int> <dbl>
## 1 HA 51 N384HA 2013 1 9 641 900 1301
## 2 MQ 3535 N504MQ 2013 6 15 1432 1935 1137
## 3 MQ 3695 N517MQ 2013 1 10 1121 1635 1126
## 4 AA 177 N338AA 2013 9 20 1139 1845 1014
## 5 MQ 3075 N665MQ 2013 7 22 845 1600 1005
## 6 DL 2391 N959DL 2013 4 10 1100 1900 960
## 7 DL 2119 N927DA 2013 3 17 2321 810 911
## 8 DL 2007 N3762Y 2013 6 27 959 1900 899
## 9 DL 2047 N6716C 2013 7 22 2257 759 898
## 10 AA 172 N5DMAA 2013 12 5 756 1700 896
## # ℹ 336,766 more rows
## # ℹ 10 more variables: arr_time <int>, sched_arr_time <int>, arr_delay <dbl>,
## # origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>, hour <dbl>,
## # minute <dbl>, time_hour <dttm>#Option C - Incorrect
select(flights, starts_with("dep"))## # A tibble: 336,776 × 2
## dep_time dep_delay
## <int> <dbl>
## 1 517 2
## 2 533 4
## 3 542 2
## 4 544 -1
## 5 554 -6
## 6 554 -4
## 7 555 -5
## 8 557 -3
## 9 557 -3
## 10 558 -2
## # ℹ 336,766 more rows#Option D - Incorrect
summarise(flights, delay=mean(dep_delay,na.rm=TRUE))## # A tibble: 1 × 1
## delay
## <dbl>
## 1 12.6#Question 3
#Option B - Correct
not_cancelled <- flights %>%
filter(!is.na(dep_delay))
not_cancelled %>%
group_by(year, month, day) %>%
summarise(mean = mean(dep_delay))## `summarise()` has grouped output by 'year', 'month'. You can override using the
## `.groups` argument.## # A tibble: 365 × 4
## # Groups: year, month [12]
## year month day mean
## <int> <int> <int> <dbl>
## 1 2013 1 1 11.5
## 2 2013 1 2 13.9
## 3 2013 1 3 11.0
## 4 2013 1 4 8.95
## 5 2013 1 5 5.73
## 6 2013 1 6 7.15
## 7 2013 1 7 5.42
## 8 2013 1 8 2.55
## 9 2013 1 9 2.28
## 10 2013 1 10 2.84
## # ℹ 355 more rows#Option D - Correct
flights %>%
group_by(year, month, day) %>%
summarise(mean = mean(dep_delay, na.rm = TRUE))## `summarise()` has grouped output by 'year', 'month'. You can override using the
## `.groups` argument.## # A tibble: 365 × 4
## # Groups: year, month [12]
## year month day mean
## <int> <int> <int> <dbl>
## 1 2013 1 1 11.5
## 2 2013 1 2 13.9
## 3 2013 1 3 11.0
## 4 2013 1 4 8.95
## 5 2013 1 5 5.73
## 6 2013 1 6 7.15
## 7 2013 1 7 5.42
## 8 2013 1 8 2.55
## 9 2013 1 9 2.28
## 10 2013 1 10 2.84
## # ℹ 355 more rows#Option C - Incorrect
not_cancelled_1 <- flights %>%
filter(!is.na(dep_delay), !is.na(arr_delay))#Option A - Incorrect
delays <- not_cancelled %>%
group_by(tailnum) %>%
summarise(
delay = mean(arr_delay)
)#Question 4
#Part 1
not_cancelled_q4 <- flights %>%
filter(!is.na(arr_delay))
avg_arr_delay_by_tail_num <- not_cancelled_q4 %>%
group_by(tailnum) %>%
summarize(avg_arr_delay = mean(arr_delay, na.rm = TRUE))
#Part 2
lowest_delay <-
avg_arr_delay_by_tail_num %>% filter(avg_arr_delay == min(avg_arr_delay, na.rm = TRUE))
lowest_delay## # A tibble: 1 × 2
## tailnum avg_arr_delay
## <chr> <dbl>
## 1 N560AS -53#Question 5
#By using the following code, you are able to get the first and last flights departure time: The wording of this question is confusing me. I know that the last flight stops at 24:00, but does that mean it left the next day or the day in question? If it counts 2400 as the same day then the answer is true, but if it doesn't then the answer is false.
not_cancelled %>%
group_by(year, month, day) %>%
summarise(
first = min(dep_time),
last = max(dep_time)
) %>% arrange(desc(last))## `summarise()` has grouped output by 'year', 'month'. You can override using the
## `.groups` argument.## # A tibble: 365 × 5
## # Groups: year, month [12]
## year month day first last
## <int> <int> <int> <int> <int>
## 1 2013 2 7 27 2400
## 2 2013 2 11 1 2400
## 3 2013 3 15 11 2400
## 4 2013 3 22 37 2400
## 5 2013 3 25 13 2400
## 6 2013 4 2 9 2400
## 7 2013 4 4 14 2400
## 8 2013 4 20 7 2400
## 9 2013 5 21 110 2400
## 10 2013 6 17 2 2400
## # ℹ 355 more rows#Question 6
flights %>%
group_by(month) %>%
summarise(
total_flights = n(),
delayed_over_hour = sum(dep_delay > 60, na.rm = TRUE),
proportion = delayed_over_hour/total_flights
)## # A tibble: 12 × 4
## month total_flights delayed_over_hour proportion
## <int> <int> <int> <dbl>
## 1 1 27004 1821 0.0674
## 2 2 24951 1654 0.0663
## 3 3 28834 2340 0.0812
## 4 4 28330 2535 0.0895
## 5 5 28796 2309 0.0802
## 6 6 28243 3494 0.124
## 7 7 29425 3820 0.130
## 8 8 29327 2295 0.0783
## 9 9 27574 1330 0.0482
## 10 10 28889 1344 0.0465
## 11 11 27268 1086 0.0398
## 12 12 28135 2553 0.0907#Question 7
flights %>%
group_by(dest) %>%
summarise(num_carriers = n_distinct(carrier)) %>%
arrange(desc(num_carriers))## # A tibble: 105 × 2
## dest num_carriers
## <chr> <int>
## 1 ATL 7
## 2 BOS 7
## 3 CLT 7
## 4 ORD 7
## 5 TPA 7
## 6 AUS 6
## 7 DCA 6
## 8 DTW 6
## 9 IAD 6
## 10 MSP 6
## # ℹ 95 more rows#Question 9
delays <- flights %>%
group_by(dest) %>%
summarise(
count = n(),
dist = mean(distance, na.rm = TRUE),
delay = mean(arr_delay, na.rm = TRUE)
) %>%
filter(count > 20, dest != "HNL")