In-class worksheet 7

Feb 12, 2019

In this worksheet, we will use the libraries tidyverse and nycflights13:

library(tidyverse)
theme_set(theme_bw(base_size=12)) # set default ggplot2 theme
library(nycflights13)

The nycflights13 package contains information about all planes departing fron New York City in 2013.

1. Joining tables

The following two tables list the population size and area (in sq miles) of three major Texas cities each:

population <- read_csv(file =
"city,year,population
Houston,2014,2239558
San Antonio,2014,1436697
Austin,2014,912791
Austin,2010,790390")
population
## # A tibble: 4 x 3
##   city         year population
##   <chr>       <int>      <int>
## 1 Houston      2014    2239558
## 2 San Antonio  2014    1436697
## 3 Austin       2014     912791
## 4 Austin       2010     790390
area <- read_csv(file =
"city,area
Houston,607.5
Dallas,385.6
Austin,307.2")
area
## # A tibble: 3 x 2
##   city     area
##   <chr>   <dbl>
## 1 Houston  608.
## 2 Dallas   386.
## 3 Austin   307.

Combine these two tables using the functions left_join(), right_join(), and inner_join(). How do these join functions differ in their results?

# R code goes here.

2. Relationship between arrival delay and age of plane

The table flights from nycflights13 contains information about individual departures:

flights
## # A tibble: 336,776 x 19
##     year month   day dep_time sched_dep_time dep_delay arr_time
##    <int> <int> <int>    <int>          <int>     <dbl>    <int>
##  1  2013     1     1      517            515         2      830
##  2  2013     1     1      533            529         4      850
##  3  2013     1     1      542            540         2      923
##  4  2013     1     1      544            545        -1     1004
##  5  2013     1     1      554            600        -6      812
##  6  2013     1     1      554            558        -4      740
##  7  2013     1     1      555            600        -5      913
##  8  2013     1     1      557            600        -3      709
##  9  2013     1     1      557            600        -3      838
## 10  2013     1     1      558            600        -2      753
## # … with 336,766 more rows, and 12 more variables: sched_arr_time <int>,
## #   arr_delay <dbl>, carrier <chr>, flight <int>, tailnum <chr>,
## #   origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>, hour <dbl>,
## #   minute <dbl>, time_hour <dttm>

Individual planes are indicated by their tail number (tailnum in the table). Calculate the mean arrival delay (arr_delay) for each tail number. Do you notice anything unusual in the result? Try to calculate the mean with and without adding the option na.rm = TRUE.

# R code goes here.

Information about individual planes is availabe in the table planes:

planes
## # A tibble: 3,322 x 9
##    tailnum  year type       manufacturer  model  engines seats speed engine
##    <chr>   <int> <chr>      <chr>         <chr>    <int> <int> <int> <chr> 
##  1 N10156   2004 Fixed win… EMBRAER       EMB-1…       2    55    NA Turbo…
##  2 N102UW   1998 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
##  3 N103US   1999 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
##  4 N104UW   1999 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
##  5 N10575   2002 Fixed win… EMBRAER       EMB-1…       2    55    NA Turbo…
##  6 N105UW   1999 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
##  7 N107US   1999 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
##  8 N108UW   1999 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
##  9 N109UW   1999 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
## 10 N110UW   1999 Fixed win… AIRBUS INDUS… A320-…       2   182    NA Turbo…
## # … with 3,312 more rows

In particular, this table lists the year each individual plane was manufactured. Make a combined table that holds tail number, mean arrival delay, and year of manufacture for each plane. Then plot mean arrival delay vs. year of manufacture.

# R code goes here.

3. Relationship between arrival delay and temperature

Now calculate the mean arrival delay for each day of the year, and store in a variable called daily_delays.

# R code goes here.

We want to correlate these delay values with the temperature of each day. The data frame weather holds temperature measurements for each hour of each day:

weather
## # A tibble: 26,115 x 15
##    origin  year month   day  hour  temp  dewp humid wind_dir wind_speed
##    <chr>  <dbl> <dbl> <int> <int> <dbl> <dbl> <dbl>    <dbl>      <dbl>
##  1 EWR     2013     1     1     1  39.0  26.1  59.4      270      10.4 
##  2 EWR     2013     1     1     2  39.0  27.0  61.6      250       8.06
##  3 EWR     2013     1     1     3  39.0  28.0  64.4      240      11.5 
##  4 EWR     2013     1     1     4  39.9  28.0  62.2      250      12.7 
##  5 EWR     2013     1     1     5  39.0  28.0  64.4      260      12.7 
##  6 EWR     2013     1     1     6  37.9  28.0  67.2      240      11.5 
##  7 EWR     2013     1     1     7  39.0  28.0  64.4      240      15.0 
##  8 EWR     2013     1     1     8  39.9  28.0  62.2      250      10.4 
##  9 EWR     2013     1     1     9  39.9  28.0  62.2      260      15.0 
## 10 EWR     2013     1     1    10  41    28.0  59.6      260      13.8 
## # … with 26,105 more rows, and 5 more variables: wind_gust <dbl>,
## #   precip <dbl>, pressure <dbl>, visib <dbl>, time_hour <dttm>

First, calculate the mean temperature for each day, and store in a variable called mean_temp:

# R code goes here.

Now combine the mean delay and the mean temperature into one table, and then plot mean delay vs. mean temperature.

# R code goes here.

4. If this was easy

Find out for how many tail numbers in the flights data set we have no information in the planes data set. What do we have to pay attention to when joining the flights and planes tables?

# R code goes here.

Calculate the mean arrival delay by plane model and by plane engine. Sort in order of descending mean delay. Remove all tailnumbers for which no plane information is available.

# R code goes here.