A variety of useful toolkits have been designed to help support information visualization applications. Some include support for the full visualization pipeline from data to interactive graphics, while others focus only on a subset, typically graphics and interaction.
Vega-Lite - A high-level visualization grammar that compiles concise specifications to full Vega specifications.
OpenFrameworks - an open-source C++ graphics library popular for video and media installations, similar approach to Processing.
Voyager – web-based data exploration tools from UW’s Interactive Data Lab
GGobi - classic system for visualizations of multivariate data
Tableau Training: Specifically the Getting Started video and Visual Analytics section. Most helpful when first getting off the ground.
Build-It-Yourself Exercises: Specifically, sections Build Charts and Analyze Data > Build Common / Advanced Chart Types, and Build Data Views From Scratch > Analyze Data are a good documentation resource.
Drawing With Numbers: blog with example walkthroughs in the Visualizations section, and Tableau Wiki has a bunch of useful links for the most common advanced exploratory / visualization Tableau techniques.
D3 In Depth: Code notebook/textbook-like blog that aims to bridge intro textbooks and D3 official documentation.
Bl.ocks: Bostock’s code-sharing platform that is the predecessor of Observable; it is the most thorough repository of D3 examples by virtue of having been around since the beginning, but note that most examples are built on D3@V4 or older.
US Health Data: central searchable repository of US health data (Center for Disease Control and National Center for Health Statistics), e.g. surveys on pregnancy, cause of death, health care access, obesity, etc.