print group name on clicking a data point in a hPlot chart with shiny

问题

I have a shiny application that shows some charts using the highcharts library in rCharts.

In some cases I have multiple graphs on a single chart which are created using the group option in hPlot.

I wish to print all the parameters of a single data point on a chart when clicking on it : the x,y and group values.

I'm attaching the code in order to achieve that:

ui.r:

library(shiny)
library(rCharts)

shinyUI(bootstrapPage(
  showOutput("chart", "highcharts"),
  textOutput("Text")
))

server.r:

library(shiny)
library(rCharts)

data = data.frame(y = sample(c(1:100),100,replace = TRUE),x = sample(c(1:10),100,replace = TRUE),z = sample(c(1:2),100,replace = TRUE))

shinyServer(function(input, output) {


  output$Text = renderText({
    res = paste(input$click$x,input$click$y,input$click$z,sep = ",")
    return(res)
  })

  output$chart <- renderChart2({
    a <- rCharts:::Highcharts$new()
    a = hPlot(
      y ~ x,
      data = data,
      group = "z",
      type = "line"
    )

    a$plotOptions(
      line = list(
        cursor = "pointer",
        point = list(
          events = list(
            click = "#! function() {
                          Shiny.onInputChange('click', {
                            x: this.x,
                            y: this.y,
                            z: this.group
                          })
                        } !#"
          )
        )
      )
    )
    a$addParams(dom = "chart")
    return(a)
  })
})

When I click on some data point i only get the x and y coordinates printed to the screen without the group variable.

What might be the cause?

maybe the call for the group variable is not this.group?

Thanks.

来源：https://stackoverflow.com/questions/27723555/print-group-name-on-clicking-a-data-point-in-a-hplot-chart-with-shiny

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