Overview

ggplot2 is a grammar of graphics, a coherent system for describing and building graphs.

• data (data frame): ggplot(dataset)
• aesthetic mapping (coordination system, color, size, line type, position etc): aes()
• geometries: geom_point, geom_line, geom_bar, …
• stat (summarization/transformation of data): stat_smooth,
• scale (map data values into computer values): scale_y_continuous(), scale_x_log10, …
• facet: facet_wrap, facet_grid
• fine tuning coordinatae, theme, labels: coordinate_*, theme_bw, labs(x=..., y=...)

Lesson

1. Data visulization with ggplot2
2. ggfortify - plot some popular R packages with ggplot2
3. geom_map
4. geom_sf - ggplot2 working with simple feature and the simple feature package for geo-spatial analysis
5. ggmap - raster map tiles from popular online mapping services
6. interactive maps and charts with R

Exercise

1. Plot the daily bike counts with ggplot2; Experiement with different options (bar, line, etc) and select the one works best for you;
2. Plot weekly, monthly, and annual bike counts for the three bridges;
3. Now think about and try out different ways to plot weather information along with your daily bike counts (separately or together);
4. You can combine time series stats and ggplot2/ggfortify to plot seasonal variation, trend and noise separately. See here for an example of how to do this.

Sample code

Resources:

1. ggplot2 tutorial by Dr. Jenny Bryan
2. R4DS Graphics for communication
3. The ggplot2 Cheat Sheet - RStudio
4. R Graphics Cookbook