Analyzing Notebook Histories to Understand Data Visualization Workflows

Visualization design is often a demanding process that involves trying different encodings, exploring different data transformations, and refining details. While there have been important studies of these workflows, the lower-level, code-intensive practices remain underexplored. Exploratory notebook tools have allowed designers to rapidly iterate on visualizations. We use publicly-available version histories of notebooks to study how users work in these environments, observing both how they build new visualizations from existing templates or previous work and how they refine visualizations over time. We examine the interplay between data manipulation and visualization, and classify the types of changes made when updating visual encodings. We also analyze the impact of different frameworks by comparing two code-oriented libraries and a chart wizard. Finally, we examine how interactions with notebooks have changed over the years, including after the widespread availability of AI. These analyses help us understand how users iterate to produce visualizations over time using different frameworks.