Suppose you want your app to react only under certain circumstances, such as when the user clicks a button. In these cases, you can use the observeEvent() or eventReactive functions. Both trigger when a specified event is fired. Let's work with our plot about the t-distribution:
library(shiny)#the UIui <- fluidPage(numericInput(inputId = "freedom",label = "Degrees of Freedom:", value = 1, min = 1, max = 50, step = 1), textInput(inputId = "title", label = "Chart title:", value = "prob. density distributions"), actionButton(inputId = "upgrade", label = "Plot it!"), plotOutput(outputId = "plot_a"))#the server functionserver <- function(input, output) { up <- eventReactive(input$upgrade, { x <- seq(-5,5,.1) ...
