using leaflet with shiny

Question

I am trying to plot a map in shiny using leaflet, but I keep getting an error that I don't understand. Below is a minimum reproducible example. Thanks in advance for your help

library(shiny)
library(leaflet)
ui = fluidPage("test", id="nav",
               leafletOutput("map", width="100%", height="100%")
               )


server <- function(input, output,session) {
  output$map <- renderLeaflet({
    print("Rendering leaflet map")
    leaflet() %>% addProviderTiles("Esri.OceanBasemap") %>% 
    fitBounds(160, -30, 185, -50)
    print("Finishing rendering leaflet map")
  })
}

shinyApp(ui, server);

I get this printed to the console:

[1] "Rendering leaflet map"
[1] "Finishing rendering leaflet map"
Warning: Error in $: $ operator is invalid for atomic vectors
Stack trace (innermost first):
    80: origRenderFunc
    79: output$map
     4: <Anonymous>
     3: do.call
     2: print.shiny.appobj
     1: <Promise>

The leaflet function seems to work when outside of the shiny framework hence why I am a little confused.

    leaflet() %>% addProviderTiles("Esri.OceanBasemap") %>% 
    fitBounds(160, -30, 185, -50)

Answer 1

A couple of points

• The last statement in the renderLeaflet() call is what is returned. So, if you have a print statement, that is what is returned, not the leaflet object
• I think you also need shinyUI() and shinyServer() wrapped around your UI and Server functions - Deprecated as of shiny v0.10
• height is a tricky argument to get right - see this thread

---

library(shiny)
library(leaflet)

ui <- fluidPage(
        leafletOutput(outputId = "map", width="100%")
        )



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

    output$map <- renderLeaflet({
        leaflet() %>% addProviderTiles("Esri.OceanBasemap") %>% 
            fitBounds(160, -30, 185, -50)
    })  
}

shinyApp(ui, server);