This small example shows a Shiny module (linked_scatter.R) and how it can be used within an application (app.R). The linked scatter module lets the caller specify the data frame (mpg) and dimensions (cty/hwy and drv/hwy) that should be plotted, and also returns a reactive expression that contains the data frame with selection info in a selected_ column. It renders two scatter plots that can be brushed (click and drag to make a selection) with coordinated highlighting between the plots.