TrendVis is a plotting package that uses matplotlib to create information-dense, sparkline-like, quantitative visualizations of multiple disparate data sets in a common plot area against a common variable. This plot type is particularly well-suited for time-series data. We discuss the rationale behind and the challenges associated with adapting matplotlib to this particular plot style, the TrendVis API and architecture, and various features available for users to customize and enhance the readability of their figures while walking through a sample workflow.