add shiny brush example

Author: cpsievert

inst/examples/brush/app.R

@@ -0,0 +1,43 @@
+library(shiny)
+library(ggplot2)
+library(dplyr)
+library(plotly)
+
+ui <- fluidPage(
+  plotOutput("scatter1", brush = brushOpts("brush", direction = "xy")),
+  plotlyOutput("plot1")
+)
+
+server <- function(input, output, session) {
+  output$scatter1 <- renderPlot({
+    iris$selected <- 1
+    if (!is.null(input$brush)) { 
+      br <- input$brush
+      x <- iris$Sepal.Length <= br$xmin | br$xmax <= iris$Sepal.Length
+      y <- iris$Sepal.Width <= br$ymin | br$ymax <= iris$Sepal.Width
+      iris$selected[x | y] <- 0.3 
+    }
+    ggplot(iris, aes(Sepal.Length, Sepal.Width, color = Species, alpha = selected)) + 
+      geom_point() + scale_alpha(guide = "none")
+  })
+  
+  output$plot1 <- renderPlotly({
+    p <- iris %>%
+      count(Species) %>%
+      plot_ly(x = Species, y = n, opacity = 0.5, type = "bar",
+              marker = list(color = toRGB("grey92"))) %>%
+      layout(barmode = "overlay", showlegend = FALSE)
+    if (!is.null(input$brush)) { 
+      br <- input$brush
+      s <- iris %>%
+        filter(br$xmin <= Sepal.Length, Sepal.Length <= br$xmax) %>%
+        filter(br$ymin <= Sepal.Width, Sepal.Width <= br$ymax) %>%
+        count(Species)
+      p <- add_trace(p, x = Species, y = n, data = s,
+                     marker = list(color = toRGB("steelblue")))
+    }
+    p
+  })
+}
+
+shinyApp(ui, server)