add persistent selection in shiny example for #1187

Author: cpsievert

inst/examples/shiny/event_data_persist/app.R

@@ -0,0 +1,36 @@
+library(shiny)
+library(plotly)
+
+ui <- fluidPage(
+  plotlyOutput("plot"),
+  verbatimTextOutput("data")
+)
+
+mtcars$id <- row.names(mtcars)
+
+server <- function(input, output, session) {
+  
+  output$plot <- renderPlotly({
+    plot_ly(mtcars, x = ~disp, y = ~mpg) %>%
+      add_markers(key = ~id) %>%
+      layout(dragmode = "select") %>%
+      highlight("plotly_selected")
+  })
+  
+  selected <- reactiveVal(rep(FALSE, nrow(mtcars)))
+  
+  selected_data <- reactive({
+    ed <- event_data("plotly_selected")
+    if (is.null(ed)) return(NULL)
+    new <- mtcars[["id"]] %in% ed[["key"]]
+    selected(selected() | new)
+    mtcars[selected(), ]
+  })
+  
+  output$data <- renderPrint({
+    selected_data()
+  })
+  
+}
+
+shinyApp(ui, server)