ObserveEvent of group legend in Shiny - r

Question

I am working on Shiny and I would like to capture with a ObserveEvent the group/BaseGroup that the user is clicking in the legend of the following map:
output$map <- renderLeaflet({
p <- leaflet(paises_total_casos()) %>%
addTiles() %>%
setView( lat=10, lng=0 , zoom=2) %>%
addCircles(lng = ~cent$x, lat = ~cent$y, weight = 1, radius = ~sqrt(total_casos) * 40, color = "blue", group = "New_cases",
label = ~htmlEscape(paste(location, ":", format(as.numeric(total_casos), big.mark=","), sep = " "))) %>%
addCircles(lng = ~cent$x, lat = ~cent$y, weight = 1, radius = ~sqrt(total_fallecidos) * 40, color = "red", group = "New_deaths",
label = ~htmlEscape(paste(location, ":", format(as.numeric(total_fallecidos), big.mark=","), sep = " "))) %>%
addCircles(lng = ~cent$x, lat = ~cent$y, weight = 1, radius = ~sqrt(tests) * 40, color = "green", group = "New_tests",
label = ~htmlEscape(paste(location, ":", format(as.numeric(tests), big.mark=","), sep = " "))) %>%
#Afegim el Layers Control
addLayersControl(baseGroups = c("New_cases", "New_deaths", "New_tests"),
options = layersControlOptions(collapsed = FALSE))
})
Let's say I would like to capture if the map is showing the group New_cases, New_deaths or New_tests.
Is there a possibility to do that with ObserveEvent?
Thank you

Answer 1

You can include an observer for your map. You can use input$map_groups (adding "_groups" to the outputId used) and place inside observe. See complete example below which will print the map layer shown.
library(shiny)
library(leaflet)
ui <- fluidPage(leafletOutput("map"))
server <- function(input, output, session) {
output$map <- renderLeaflet({
leaflet() %>%
addTiles(group = "OpenStreetMap") %>%
addProviderTiles("Stamen.Toner", group = "Toner by Stamen") %>%
addMarkers(runif(20, -75, -74), runif(20, 41, 42), group = "Markers") %>%
addLayersControl(
baseGroups = c("OpenStreetMap", "Toner by Stamen"),
overlayGroups = c("Markers")
)
})
observe({
print(input$map_groups)
})
}
shinyApp(ui, server)