How to create an event when pressing on a leaflet popup in R?

Question

I would like to make the tabPanel change in Shiny when I click on a Leaflet polygon. I have a couple of ideas on how to do this, but I can't find the information I need to implement them. I have the leaflet in a tabPanel, but I would like to switch to another tab when a polygon is clicked on.

    leaflet(llmap) %>%
      addTiles() %>%
      addPolygons(stroke = F,
                  fillOpacity = .8,
                  smoothFactor = .5,
                  color=~pal(x),
                  popup = pop)

I thought of making popup=updateTabsetPanel(session="New Tab"), but that doesn't work. My other idea is to call updateTabsetPanel(session="New Tab") anytime the user clicks on a new polygon, but I don't know what event I would need to return to let it know that a new polygon was clicked or even if a new popup popped up. Does anyone know this?

Answer 1

Here's an example of a reactive function that updates when you click a polygon:

output$myMap <- renderLeaflet({
    map_out() #this is just a function that returns a leaflet map
  })


output$MyGraph <- renderPlot({  
    event <- input$myMap_shape_click #Critical Line!!!

    ... #Code to run here

    GraphData <- GraphData[event$id] # subsetting example

    }
  })  

A few things to note here:

1. the input$myMap_shape_click changes based on what you call your map above. I called it myMap, so the structure is as shown. If you used output$YourMap to initialize, the click would be called with input$YourMap_shape_click

2. the id of the polygon that you click on can be accessed with event$id. This can be really useful for subsetting + graphing based on a polygon that is clicked. Also accessible are event$lat and event$lng

3. the renderPlot can be any reactive function. If its not tied to a specific output, you can just use observe as below. This way, your code will run anytime a polygon is clicked. This is because the value of input$myMap_shape_click changes every time you click.

I haven't used updateTabsetPanel before, but I'd imagine this will work:

observe({

  event <- input$myMap_shape_click

  updateTabsetPanel(session, "inTabset", selected = event$id)

}) 

which would switch the tab to a panel with the same id as the polygon you clicked.