Interactive plotting in shiny using mouse clicks

Question

I am doing a project where I use the shiny server and connect R to mongodb to fetch results from database and display it dynamically.

However, I face the following probl

Answer 1

Here's a simple example that demonstrates the behavior you want, just run this code (or save as a file and source it). This code uses the new observeEvent function that debuted in Shiny 0.11, which just hit CRAN over the weekend.

The basic idea is that we track two reactive values, click1 and range. click1 represents the first mouse click, if any exists; and range represents the x-values of both mouse clicks. Clicking on the plot simply manipulates these two reactive values, and the plotting operation reads them.

library(shiny)

ui <- fluidPage(
  h1("Plot click demo"),
  plotOutput("plot", clickId = "plot_click"),
  actionButton("reset", "Reset zoom")
)

server <- function(input, output, session) {
  v <- reactiveValues(
    click1 = NULL,  # Represents the first mouse click, if any
    range = NULL    # After two clicks, this stores the range of x
  )

  # Handle clicks on the plot
  observeEvent(input$plot_click, {
    if (is.null(v$click1)) {
      # We don't have a first click, so this is the first click
      v$click1 <- input$plot_click
    } else {
      # We already had a first click, so this is the second click.
      # Make a range from the previous click and this one.
      v$range <- range(v$click1$x, input$plot_click$x)
      # And clear the first click so the next click starts a new
      # range.
      v$click1 <- NULL
    }
  })

  observeEvent(input$reset, {
    # Reset both the range and the first click, if any.
    v$range <- NULL
    v$click1 <- NULL
  })

  output$plot <- renderPlot({
    plot(cars, xlim = v$range)
    if (!is.null(v$click1$x))
      abline(v = v$click1$x)
  })
}

shinyApp(ui, server)