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Stat 437 HW2
Your Name (Your student ID)
General rule
Due by 11:59pm Pacific Standard Time, Feb 17, 2021. Please show your work and submit your
computer codes in order to get points. Providing correct answers without supporting details does
not receive full credits. This HW covers:
• Advanced Visualizations via ggplot2: adjusting legends, fonts, orientation, and math expressions
• Visualizing networks as graphs
• Interactive visualization

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Stat 437 HW2
Your Name (Your student ID)
General rule
Due by 11:59pm Pacific Standard Time, Feb 17, 2021. Please show your work and submit your
computer codes in order to get points. Providing correct answers without supporting details does
not receive full credits. This HW covers:
• Advanced Visualizations via ggplot2: adjusting legends, fonts, orientation, and math expressions
• Visualizing networks as graphs
• Interactive visualization
You DO NOT have to submit your HW answers using typesetting software. However, your answers
must be legible for grading. Please upload your answers to the course space.
Problem 1
Please refer to the NYC flight data nycflights13 that has been discussed in the lecture notes and
whose manual can be found at https://cran.r-project.org/web/packages/nycflights13/index.html.
We will use flights, a tibble from nycflights13.
You are interested in looking into the average arr_delay for 4 different month 12, 1, 7 and 8, for 3
different carrier “UA”, “AA” and “DL”, and for distance that are greater than 700 miles, since
you suspect that colder months and longer distances may result in longer average arrival delays.
Note that you need to extract observations from flights, and that you are required to use dplyr
for this purpose.
The following tasks and questions are based on the extracted observations.
(1.a) For each combination of the values of carrier and month, obtain the average arr_delay
and obtain the average distance. Plot the average arr_delay against the average distance, use
carrier as facet; add a title “Base plot” and center the title in the plot. This will be your base
plot, say, as object p. Show the plot p.
(1.b) Modify p as follows to get a plot p1: connect the points for each carrier via one type of dashed
line; code the 3 levels of carrier as α1, β1,2 and γ
[0], and display them in the strip texts; change
the legend title into “My ζ” (this legend is induced when you connect points for each carrier by a
type of line), and put the legend in horizontal direction at the bottom of the plot; add a title “With
math expressions” and center the title in the plot. Show the plot p1.
(1.c) Modify p1 as follows to get a plot p2: set the font size of strip text to be 12 and rotate the
strip texts counterclockwise by 15 degrees; set the font size of the x-axis text to be 10 and rotate
the x-axis text clockwise by 30 degrees; set the x-axis label as “µˆ for mean arrival delay”; add a
title “With front and text adjustments” and center the title in the plot. Show the plot p2
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Problem 2
This problem requires you to visualize the binary relationship between members of a karate club as
an undirected graph. Please install the R library igraphdata, from which you can obtain the data
set karate and work on it. Create a graph for karate. Once you obtain the graph, you will see
that each vertex is annotated by a number or letter. What do the numbers or letters refer to? Do
you see subgraphs of the graph? If so, what do these subgraphs mean?
Problem 3
This problem requires to to create an interactive plot using plotly. If you want to display properly
the plot in your HW answers, you may well need to set your HW document as an html file (instead
of doc, docx or pdf file) when you compile your R codes.
Please use the mpg data set we have discussed in the lectures. Create an interactive, scatter plot
between “highway miles per gallon” hwy (on the y-axis) and “engine displacement in litres” displ
(on the x-axis) with the color aesthetic designated by “number of cylinders” cyl, and set the
x-axis label as “highway miles per gallon” and y-axis label as “highway miles per gallon”. You need
to check the object type for cyl and set it correctly when creating the plot. Add the title “# of
cylinders” to the legend and adjust the vertical position of the legend, if you can. For the last, you
may look through https://plotly.com/r/legend/ for help.
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