Ploting with ggplot

Overview

Teaching: 10 min
Exercises: 0 min

Questions

• How to plot in R using ggplot2 package

Objectives

• Learn professional plotting tool in R using ggplot2

• Learn multiple way to use ggplot2

What is ggplot

• Grammar of Graphics by Leland Wilkinson
• Written by Hadley Wickham - a grad student at Iowa State
• Third graphic system in for R (along with Base and Lattice)

  > install.packages("ggplot2")
  > library(ggplot2)
  

Basic component of ggplot

• A data frame
• aes: aesthetic mappings showing how data are mapped to color, size
• geoms: geometric objects like points, lines, shapes.
• facets: for conditional plots.
• stats: statistical transformations like binning, quanti les, smoothing.
• scales: what scale an aesthetic map uses
• coordinate system

Type of ggplot

• Basic qplot ```
• Same as plot in Base plot
• Nicer graphics than Base plot
• Difficult for customize ```
• Advanced ggplot ```
• Flexible with many built-in function ```

Key Points

• ggplot2