R Shiny ggplot brush

Question

How to make the brush work and highlight the selected points as red.

It seems the brushedPoints function is not working properly.

library(shiny)
library(ggplot2)


server <- function(input, session, output) {

  D = reactive({
    brushedPoints(mtcars,input$brush_1, allRows = TRUE)
  })

  output$Plot = renderPlot({
    set.seed(1)
    X = D()
    X[,"cyl"] = as.character(X[,"cyl"])

    ggplot(X,aes_string(x="cyl",y="mpg")) + 
      geom_boxplot(outlier.shape = NA) + 
      geom_jitter(aes(color = selected_))+
      scale_color_manual(values = c("black","red"),guide=FALSE)

  })

  output$log = renderPrint({
    input$brush_1
  })

  output$Data = renderPrint({
    D()
  })
}

ui <- fluidPage(
  plotOutput("Plot",brush = "brush_1"),
  verbatimTextOutput("Data"),
  verbatimTextOutput("log")

)

shinyApp(ui = ui, server = server)

Answer 1

The problem exist because you use different data in brushedPoints and ggplot : convert column to character

You can try edit data before brushedPoints

library(shiny)
library(ggplot2)


server <- function(input, session, output) {
  mt=mtcars
  mt[,"cyl"] = as.character(mt[,"cyl"])
  D=reactive({brushedPoints(mt,brush = input$brush_1,  allRows = TRUE)})

  output$Plot = renderPlot({
    set.seed(1)
      X <- D()
     ggplot(X,aes_string(x="cyl",y="mpg")) + 
      geom_boxplot(outlier.shape = NA) + 
      geom_jitter(aes(color = selected_))+
      scale_color_manual(values = c("black","red"),guide=FALSE)

  })

  output$log = renderPrint({
    input$brush_1
  })

  output$Data = renderPrint({
    D()
  })
}

ui <- fluidPage(
  plotOutput("Plot",brush = "brush_1"),
  verbatimTextOutput("Data"),
  verbatimTextOutput("log")

)

shinyApp(ui = ui, server = server)

PS

for box plot brush work not plain , because all x-coordinates - discrete you can select it only if select middle of box ( point placed not in real position but shifted to left or right - because of geom_jitter)

As told here there is no way to use geom_jitter and brush