How to make Shiny leaflet map react to change in Input value R

Question

I have the below ui.R and server.R

I have a simple dataset with 3 columns: Type of person, Longitude, Latitude

I want the Leaflet Map to react to a change in "Type of Person" <<< This is where i am stuck. I know i need to use some sort of observeEvent but not sure how to implement this.

ui.R

ui <- fluidPage(
  selectInput(inputId = "Selector",
              label = "Please Select Type of Person",
              choices = c("Please Select:",
                          "Type A",
                          "Type B"),
              selected = "Please Select:"),
  
  leafletOutput("myMap")
)

shinyApp(ui=ui, server=server)

server.R

library(shiny)

server <- function(input,output){
  
  output$myMap <- renderLeaflet({
    
    leaflet() %>%
      addTiles()%>%
      addMarkers(data=SampleData,
                 ~Longitude,
                 ~Latitude)
  })

}

Answer 1

Not exactly sure what you want your map to do, but it sounds like you are looking for leafletProxy. For example, suppose you want to clear your markers and add new ones. When you use addMarkers, be sure to include the group parameter:

(Edited to provide a complete reproducible example. Note that the answer I gave previously is unchanged, I just added the data and the rest of the shiny app structure. Note also that the 'Please Select:' part is treated as a valid choice here, there are better ways to handle the select, but that is not what this question is about.)

library(shiny)
library(leaflet)

SampleData <- data.frame(type = c('Type A', 'Type B', 'Type A', 'Type B'),
                         Longitude = c(80.1, 80.2, 80.3, 80.4),
                         Latitude = c(40.1, 40.2, 40.3, 40.4))


ui <- fluidPage(
  selectInput(inputId = "Selector",
              label = "Please Select Type of Person",
              choices = c("Please Select:",
                          "Type A",
                          "Type B"),
              selected = "Please Select:"),

  leafletOutput("myMap")
)


server <- function(input,output){

  output$myMap <- renderLeaflet({

    leaflet() %>%
      addTiles()%>%
      addMarkers(data=SampleData,
                 ~Longitude,
                 ~Latitude,
                 group = "myMarkers")
  })


  observeEvent(input$Selector, {
    leafletProxy("myMap") %>%
      clearGroup("myMarkers") %>%
      addMarkers(data = SampleData[SampleData$type == input$Selector, ],
                 ~Longitude,
                 ~Latitude,
                 group = "myMarkers")
  })

}
shinyApp(ui, server)