16.3 Click leaflet map

Some info about using leaflet with shiny. https://rstudio.github.io/leaflet/shiny.html

Example of clicking on a leaflet map and getting coordinates

Code

library(shiny)
library(leaflet)
library(tidyverse)

# Define UI
ui <- fluidPage(
  titlePanel("Example"),
  mainPanel(leafletOutput("map"))
)

# Define server logic, and account for User interaction
server <- function(input, output, session) {
  output$map <- renderLeaflet({ 
    mymap <- leaflet() %>% 
      addTiles() %>% 
      setView(lng = -73.95, 
              lat = 40.73, 
              zoom = 12)
    mymap
  })
  
  # when map is clicked, get the coordinates and show marker on the map 
  observeEvent(input$map_click, {
    click <- input$map_click
    
    ## print coords to the console
    print(click)
    
    ## display the click on the map
    proxy <- leafletProxy("map")
    proxy %>% 
      clearGroup("new_point") %>% ## remove the previous point
      addCircles(click$lng, 
                 click$lat,
                 radius = 100, 
                 color  = "red", 
                 group  = "new_point")
  })
}

shinyApp(ui = ui, server = server)