Explore the relationship between horsepower and mpg

Rui Wang
Mar-01-2020

Product Overview

The main idea behind this product is helping user explore the relationship between hp and mpg. And it also provided the visual camparision between simple linear model and ploynomial linear model.

sidebar panel
- adjusting hp
- displaying selected cars' name, hp and mpg
main panel
- Boxplot
- Scatterplot with regression line

Boxplot Information

The boxplot displayed the basic HorsePower information using boxplot. The redpoint on the boxplot corresponde with the hp slider value. This design was created for quick spot on where the selected value lies compared to the all cars' hp data.

library(ggplot2)
ggplot(mtcars, aes(x = 1, y = mpg)) + 
    geom_boxplot(width = 0.3) + 
    scale_x_continuous("", breaks = NULL) + 
    coord_flip()

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Scatter Plot Information Part 1

Because of the limitation of the presentation, I can not echo the code here. Please check my github repo for the source code file for this part.

Select Model Lines Displayed On the Plot

The scatter plot mapped the hp and mpg on x and y axis respectively, and user could also add the simple linear model regression line (red) and polynomial linear model (blue) on it. As user selecting different hp value, the predicted point based on two models will move correspondingly.
Select Points On The Plot

Beside displaying two different model lines on scatter plot. Users could also directly selecte points through the scatter plot. And the selected points will display the cars' corresponding information on the left side bar area as a dataframe format.

Scatter Plot Information Part 2

This part provide some additional information about the two different model lines used in the analysis product. Users could clearly spot the prediction points moving on the two different lines, and compare their differences.

Simple Linear Model (Red)

Created by formula lm(mpg ~ hp), and shows exactly a straight line on the plot.
Polynomial Linear Model (Blue)

Created by formula lm(mpg ~ poly(hp, 2)), and shows a curve line on the plot.

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