library(tidyverse)
library(nycflights13)
library(lubridate)


1. nycflights13 data set

Question : How many timezones are there for all the destination airports (excluding NA)?

airports1 <- airports %>%
  select(faa, tzone,tz) 

flights %>%
  left_join(airports1, by = c("dest" = "faa")) %>%
  rename("dest_tzone" = "tzone","dest_tz" = "tz") %>%
  filter(!is.na(dest_tzone))%>%
  count(dest_tzone)%>%
  print()
## # A tibble: 7 × 2
##   dest_tzone               n
##   <chr>                <int>
## 1 America/Anchorage        8
## 2 America/Chicago      74811
## 3 America/Denver       10291
## 4 America/Los_Angeles  46324
## 5 America/New_York    192377
## 6 America/Phoenix       4656
## 7 Pacific/Honolulu       707

Answer: there are 7 timezones: America/Anchorage, America/Chicago, America/Denver, America/Los_Angeles,America/New_York, America/Phoenix, Pacific/Honolulu


Question : Use the data in flights and airports only along with R code to show the time difference (in hours)between New York City and the following cities:

– Chicago – Dallas – Denver – Seattle – Anchorage

airports2 <- airports %>%
  select(faa, tzone,tz) 
flights %>%
  left_join(airports2, by = c("dest" = "faa")) %>%
  rename("dest_tzone" = "tzone","dest_tz" = "tz") %>%
  select(dest,dest_tzone,dest_tz) %>%
  filter( dest == "ORD" | dest == "PHX" | dest == "DEN" | dest == "SEA" | dest == "ANC")
## # A tibble: 33,136 × 3
##    dest  dest_tzone      dest_tz
##    <chr> <chr>             <dbl>
##  1 ORD   America/Chicago      -6
##  2 ORD   America/Chicago      -6
##  3 ORD   America/Chicago      -6
##  4 PHX   America/Phoenix      -7
##  5 PHX   America/Phoenix      -7
##  6 ORD   America/Chicago      -6
##  7 DEN   America/Denver       -7
##  8 ORD   America/Chicago      -6
##  9 ORD   America/Chicago      -6
## 10 ORD   America/Chicago      -6
## # … with 33,126 more rows
flights %>%
  left_join(airports2, by = c("dest" = "faa")) %>%
  rename("dest_tzone" = "tzone","dest_tz" = "tz") %>%
  select(dest,dest_tzone,dest_tz) %>%
  filter( dest == "ORD" | dest == "PHX" | dest == "DEN" | dest == "SEA" | dest == "ANC") %>%
  summarise(dest=dest, time_diff = -5 - dest_tz) %>%
  print()
## Warning: Returning more (or less) than 1 row per `summarise()` group was deprecated in
## dplyr 1.1.0.
## ℹ Please use `reframe()` instead.
## ℹ When switching from `summarise()` to `reframe()`, remember that `reframe()`
##   always returns an ungrouped data frame and adjust accordingly.
## # A tibble: 33,136 × 2
##    dest  time_diff
##    <chr>     <dbl>
##  1 ORD           1
##  2 ORD           1
##  3 ORD           1
##  4 PHX           2
##  5 PHX           2
##  6 ORD           1
##  7 DEN           2
##  8 ORD           1
##  9 ORD           1
## 10 ORD           1
## # … with 33,126 more rows

Answer: the time difference between New Your and the cities are: Chicago 1hr, Dallas 2hrs, Denver 2hrs, Seattle 3hrs, Anchorage 4hrs.


Question : Write a function Time_difference_NYC(dest) to compute the time difference (in hours) between any destination airport (in faa code) and New York City.

Time_difference_NYC <- function(x){
    nyc_tz = -5
    #for (i in airports$faa) {
      #airport_tz <- airports[(airports$faa== "i"), ]$tz
    airports[airports$faa == x, ]$tz - nyc_tz
      
} 
Time_difference_NYC("LAX")
## [1] -3


Question : Write a function flight_time(dep_time, arr_time, origin, dest) to compute the actual flight time from the dep_time at the origin airport to the arr_time in the dest airport. dep_time and arr_time should be in the form of an integer such as 830 (8:30am); origin and dest should be in faa codes.


Question : Write a function flights_distribution(month, day) which creates a histogram of flight counts vs hour for the given month and day in 2013.

flights1 <- flights
flights_distribution <- function(m, d) {
flights1 %>% 
  filter(month == m & day == d & year == 2013) %>%
  ggplot(aes(x = hour)) +
    geom_histogram(binwidth = 1, fill = "orange", col = "lightblue") +
    labs(x = "Hour of Day", y = "Flight Counts", title = "Flight Distribution for the given Month and Day")

  }
flights_distribution(11, 24)

flights_distribution(7, 14)


Question : Use your function in the last step to discuss how distribution of flight times within a day change over the course of the year?

flights_distribution(1, 1)

flights_distribution(2, 1)

flights_distribution(3, 1)

flights_distribution(4, 1)

flights_distribution(5, 1)

flights_distribution(6, 1)

flights_distribution(7, 1)

flights_distribution(8, 1)

flights_distribution(9, 1)

flights_distribution(10, 1)

flights_distribution(11, 1)

flights_distribution(12, 1)

Answer: according to the 12 plots above(they are the first day distribution for 12 month), the similar parts are from 22pm ~ 5am, the flights are very few, starting from 6am, there will be a big surge, for the majority month, 6~8am are the busiest schedule, except Jan. and Sept, the busiest schedule are from 3~5pm; I also check the Sunday distributions for all the month, the highest peak is not as early as 6am, it is around 8am and 3pm.


2. Lists


Question : Write a code to create a list that contains 100 vectors, where the first vector is 1 alone, the second is 1 and 2, the third is 1,2,3 etc.

x <- 1:100
for ( i in x){
  print(c(1:i))
}
## [1] 1
## [1] 1 2
## [1] 1 2 3
## [1] 1 2 3 4
## [1] 1 2 3 4 5
## [1] 1 2 3 4 5 6
## [1] 1 2 3 4 5 6 7
## [1] 1 2 3 4 5 6 7 8
## [1] 1 2 3 4 5 6 7 8 9
##  [1]  1  2  3  4  5  6  7  8  9 10
##  [1]  1  2  3  4  5  6  7  8  9 10 11
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12
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## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67
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##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
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## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88
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## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
## [51] 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
## [76] 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
##   [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18
##  [19]  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36
##  [37]  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54
##  [55]  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70  71  72
##  [73]  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90
##  [91]  91  92  93  94  95  96  97  98  99 100


3. Iteration. : Use map function to select features from your midterm project data set:


Question : For all numeric variables, pick up those that return a p-value less than 0.01 when do the two population mean t-test

CC_data <- read_csv("application_data.csv")
## Rows: 307511 Columns: 122
## ── Column specification ────────────────────────────────────────────────────────
## Delimiter: ","
## chr  (16): NAME_CONTRACT_TYPE, CODE_GENDER, FLAG_OWN_CAR, FLAG_OWN_REALTY, N...
## dbl (106): SK_ID_CURR, TARGET, CNT_CHILDREN, AMT_INCOME_TOTAL, AMT_CREDIT, A...
## 
## ℹ Use `spec()` to retrieve the full column specification for this data.
## ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
column_num <- map_lgl(CC_data, is.numeric) 
CC_num <- CC_data[column_num]  

results_cor <- map_dbl(CC_num, ~ cor(CC_num$SK_ID_CURR, .))
results_cor_data <- as.tibble(results_cor)
## Warning: `as.tibble()` was deprecated in tibble 2.0.0.
## ℹ Please use `as_tibble()` instead.
## ℹ The signature and semantics have changed, see `?as_tibble`.
results_cor_data_1<- filter(results_cor_data,abs(value) < 0.01)
results_cor_data_1
## # A tibble: 44 × 1
##        value
##        <dbl>
##  1 -0.00211 
##  2 -0.00113 
##  3 -0.00182 
##  4 -0.000343
##  5  0.000849
##  6 -0.00150 
##  7  0.00137 
##  8 -0.000973
##  9 -0.000384
## 10  0.00280 
## # … with 34 more rows


Question : For all categorical variables (other than the target variable), pick up those that return a p-value less than 0.01 when do the chi-square test.


CC_data <- read_csv("application_data.csv")
## Rows: 307511 Columns: 122
## ── Column specification ────────────────────────────────────────────────────────
## Delimiter: ","
## chr  (16): NAME_CONTRACT_TYPE, CODE_GENDER, FLAG_OWN_CAR, FLAG_OWN_REALTY, N...
## dbl (106): SK_ID_CURR, TARGET, CNT_CHILDREN, AMT_INCOME_TOTAL, AMT_CREDIT, A...
## 
## ℹ Use `spec()` to retrieve the full column specification for this data.
## ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
column_chr <- map_lgl(CC_data, is.character) 
CC_chr <- CC_data[column_chr] 


result <- map_dbl(CC_chr, ~chisq.test(CC_chr$NAME_CONTRACT_TYPE, .)$p.value)
## Warning in chisq.test(CC_chr$NAME_CONTRACT_TYPE, .): Chi-squared approximation
## may be incorrect

## Warning in chisq.test(CC_chr$NAME_CONTRACT_TYPE, .): Chi-squared approximation
## may be incorrect

## Warning in chisq.test(CC_chr$NAME_CONTRACT_TYPE, .): Chi-squared approximation
## may be incorrect

## Warning in chisq.test(CC_chr$NAME_CONTRACT_TYPE, .): Chi-squared approximation
## may be incorrect
result1 <- as.tibble(result)
result2 <- filter(result1,abs(value) < 0.01)
result2
## # A tibble: 12 × 1
##        value
##        <dbl>
##  1 0        
##  2 4.25e- 14
##  3 1.25e-303
##  4 1.02e- 12
##  5 1.05e-250
##  6 2.74e-301
##  7 1.14e-152
##  8 5.42e- 47
##  9 2.09e-133
## 10 1.06e- 12
## 11 1.23e-258
## 12 7.30e-  5