Ex-2-1: Data Visualization

1 Basics

1.1 Exercise 1

Objective: Create a scatter plot of miles-per-gallon (mpg) against horsepower (hp), colored by the number of cylinders (cyl). Make the size of the points larger than the default (you can pick any value as long as it is larger than the default).

Work here

Here is the output you should be getting:

Answer

ggplot(data = mtcars) +
  geom_point(aes(x = hp, y = mpg, color = as.factor(cyl)), size = 2)

1.2 Exercise 2

Objective: Create a boxplot showing the distribution of petal lengths (Petal.Length) for each species (Species). Make the color of the borders of the boxes red.

Work here

Here is the output you should be getting:

Answer

ggplot(data = iris) +
  geom_boxplot(aes(x = Species, y = Petal.Length, fill = Species), color = "red") 

1.3 Exercise 3

Objective: Create a histogram of diamond prices (price) by cut (the fill color of the histogram differs by cut). Use alpha = 0.6 so that the histograms are slightly transparent.

Work here

Here is the output you should be getting:

Answer

ggplot(data = diamonds) +
  geom_histogram(
    aes(x = price, fill = cut),
    alpha = 0.6,
    bins = 50
  )

1.4 Exercise 4

Objective: Create a line plot that shows the progression of weight (weight) over time (Time) for each of the chicks that were fed Diet 1 (Hint: you first need to filter the data so that you only have the observations that has Diet == 1). Make the line color dependent on Chick.

Work here

Here is the output you should be getting:

Answer

ggplot(data = ChickWeight %>% filter(Diet == 1)) +
  geom_line(aes(x = Time, y = weight, color = Chick))

2 Faceted figures

2.1 Exercise 1

Objective: Create a scatter plot of miles-per-gallon (mpg) against weight (wt), colored by the number of gears (gear). Facet the plot by the number of cylinders (cyl).

Work here

Here is the output you should be getting:

Answer

ggplot(data = mtcars) +
  geom_point(aes(x = wt, y = mpg, color = as.factor(gear))) +
  facet_wrap(~cyl)

2.2 Exercise 2

Objective: Create a boxplot of diamond prices (price) for each diamond cut (cut). Facet the plot by diamond color (color).

Work here

Here is the output you should be getting:

Answer

ggplot(data = diamonds) +
  geom_boxplot(aes(x = cut, y = price, fill = cut)) +
  facet_wrap(~color)

2.3 Exercise 3

Objective: Plot the progression of weight (weight) over time (Time) for each chick using a line plot. Facet the visualization by the diet type (Diet).

Work here

Here is the output you should be getting:

Answer

ggplot(data = ChickWeight) +
  geom_line(aes(x = Time, y = weight, group = Chick)) +
  facet_wrap(~Diet)

2.4 Exercise 4

Objective: Create a scatter plot of highway miles-per-gallon (hwy) against engine displacement (displ). Facet the plot by the drive type (drv), with different panels for each type of drive (front-wheel drive, rear-wheel drive, and four-wheel drive).

Work here

Here is the output you should be getting:

Answer

ggplot(data = mpg) +
  geom_point(aes(x = displ, y = hwy, color = class)) +
  facet_wrap(~drv)

2.5 Exercise 5

Objective: Plot a boxplot showing the count of insects (count) for each spray type (spray). Facet the plot by spray type (spary).

Work here

Here is the output you should be getting:

Answer

ggplot(data = InsectSprays) +
  geom_boxplot(aes(x = spray, y = count, fill = spray)) +
  facet_wrap(~spray)