Deploying and updating front end database applications
By using this library, changing input values will naturally cause the right parts of your R code to be reexecuted, which will in turn cause any changed outputs to be updated.
Reactive programming is a coding style that starts with reactive values–values that change over time, or in response to the user–and builds on top of them with reactive expressions–expressions that access reactive values and execute other reactive expressions.
In the next section we’ll complete the application by specifying the user-interface and implementing the server script.
The application we’ll be building uses the mtcars data from the R datasets package, and allows users to see a box-plot that explores the relationship between miles-per-gallon (MPG) and three other variables (Cylinders, Transmission, and Gears).
This example has a bit more going on: two inputs and two types of textual output.The previous examples have given you a good idea of what the code for Shiny applications looks like.We’ve explained a bit about reactivity, but mostly glossed over the details.The user interface definition has been updated to include a text-input field that defines a caption.
Other than that it’s very similar to the previous example: We’ve reviewed a lot code and covered a lot of conceptual ground in the first three examples.
A Shiny application is simply a directory containing a user-interface definition, a server script, and any additional data, scripts, or other resources required to support the application.