Problem Set 1

Visualization Process

Questions

1. Draw a pie chart showing the proportion of cars from the mtcars data set that have different carb values.

library(ggplot2)
ggplot(data=mtcars, 
       aes(x = factor(1), fill = factor(carb))) + 
  ylab("Proportions of cars by carb value") + xlab("") +
  geom_bar(width = 1) + 
  coord_polar(theta = "y")

knitr::include_graphics("IMG_3074.JPG")

2. Draw a bar graph, that shows the number of each gear type in mtcars.

ggplot(data=mtcars,aes(x=gear)) + geom_bar(stat="Count",colour="#FF9999") + ggtitle("Number of each Gear type in mtcars")

knitr::include_graphics("IMG_3075.JPG")

3. Next show a stacked bar graph of the number of each gear type and how they are further divded out by cyl.

ggplot(mtcars, 
       aes(x = factor(gear), fill = factor(cyl))) +  
  xlab("Gears") +
  ylab("Cylinders") +  geom_bar()

knitr::include_graphics("IMG_3076.JPG")

4. Draw a scatter plot showing the relationship between wt and mpg.

ggplot(mtcars, aes(x = wt, y = mpg)) +
  xlab("Car Weight") + ylab("mpg") +
  geom_point() +
  geom_line() +
  ggtitle(" Car Weight vs Miles Per Gallon") +
  stat_smooth(method ='lm')

knitr::include_graphics("IMG_3077.JPG")

5. Design a visualization of your choice using the data.

plot(mtcars$disp, mtcars$mpg, xlab="Engine displacement", ylab="mpg", main="MPG vs engine displacement", las=1)

knitr::include_graphics("IMG_3078.JPG")