I'm learning about Shiny app development and want to understand how to visualize the reactive flow and how Shiny efficiently updates. Using 'Mastering Shiny', identify the recommended R package for reactive graph visualization and explain the core mechanism Shiny uses to optimize updates when user inputs change.
Navigate to 'mastering-shiny.org'. Locate and navigate to 'Chapter 14: The reactive graph'. In Chapter 14, find the section that introduces reactive graph visualization and identify the recommended package. Locate the section explaining how Shiny handles input changes and read it to understand the update optimization mechanism. State the recommended package and describe Shiny's update optimization mechanism.
Identify 'reactlog' as the recommended package for visualizing the reactive graph. Explain that Shiny ensures minimal work through an 'invalidation phase' where it marks affected components as 'dirty' and only re-executes those parts of the reactive graph that are truly dependent on the changed input, thereby avoiding unnecessary computations.