This book is about the construction of heat maps using the popular statistical programming language R. Heat maps are valuable tools for exploratory data analyses in many different applications, such as gene expression levels or stock market data. Together with powerful clustering methods, heat maps are being used to visually detect interesting patterns at one glance, even in very large data sets with hundreds of variables.
This book is a hands-on guide to provide you with a practical approach to construct such powerful heat maps. You will explore the advanced features of heat maps step-by-step, and detailed explanations on the underlying code at the end of each recipe will provide you with enough information to frame those heat maps as per your needs.
Creating your first heat map in R (Simple) will help you create your first heat maps from a small data set provided in R. You will use different heat map functions in R to get a first impression of their functionalities.
Reading data from different file formats (Intermediate) will help you learn how to read data from various popular file formats. After you have created your first heat maps, it is important to learn how to get your own data into R using differently formatted datasets.
Customizing heat maps (Intermediate) will help you explore more advanced functions to customize the layout of the heat maps. The main focus lies on the usage of different color palettes, but we will also cover other useful features, such as cell notes that will be used in this recipe.
Drawing choropleth maps and contour plots (Intermediate) will help you learn to create choropleth maps of the United States and other countries. Choropleth maps are a great way to visualize data from different regions on a geographical map. Also, you will learn how to visualize a 3D surface using a contour plot.
Exporting for presentation (Simple) will help you export heat maps in various popular image formats. By comparing images with different resolutions and file sizes, you will learn how to find the best-suited format for presenting your heat map.
Bringing your data to life (Advanced) will help you learn how to manipulate heat map image files to add interactivity, such as mouse-over and hover effects and fading in of supporting information.