Reactive contexts

Reactive values are special constructs in Shiny; they are not seen anywhere else in R programming. As such, they cannot be used in just any R code, reactive values can only be accessed within a reactive context.

This is the reason why any variable that depends on a reactive value must be created using the reactive() function, otherwise you will get an error. The shiny server itself is not a reactive context, but the reactive() function, the observe() function, and all render*() functions are.

You are provided with a Shiny app containing two numeric inputs, num1 and num2, and a text output. Your task is to:

In a reactive variable called my_sum, calculate the sum of the two numeric inputs (line 10).
In a reactive variable called my_average, calculate the average of the two inputs (line 14).
In the text output, display the calculated average using the reactive variables (line 23).

Exercise

Reactive contexts

Instructions