4.2 Grammar components & ggplot2 (1)
- Let’s go into detail (Wickham 2016, 4–5)
- Data & aesthetic mappings
- data you want to visualize
- aesthetic mappings: describe how variables are mapped to aesthetic attributes that you can perceive
- Geometric objects (geoms): what you actually see on the plot: points, lines, etc.
- Statistical transformations (stats): Summarize data in many useful ways (e.g., LM)
- Scales: map values in the data space to values in an aesthetic space
- e.g., color, size or shape
- Scales draw legend or axes (allow us to decode graph)
- Coordinate system (coord): describes how data coordinates are mapped to plane of graphic22
- Provides axes/gridlines to make it possible to read the graph
- Faceting specification: how to break up data and visualize subsets
- Theme: Control finer points of display (e.g., font, background color etc.)
Wickham, Hadley. 2016. Ggplot2: Elegant Graphics for Data Analysis. Springer.