Duplicate legends when using addGeoJSONChoropleth in Shiny

[neon-ninja]

When using addGeoJSONChoropleth in an R Shiny application, changing the colormap seems to result in a extra legend for each previously chosen colormap. Problem seems to occur both on the CRAN version and github master.

Live example: https://uoacer.shinyapps.io/GeoJSONChoropleth_test/

R version 3.6.3

Code to reproduce:

library(leaflet.extras)
library(shiny)
library(RColorBrewer)

ui <- bootstrapPage(
  tags$style(type = "text/css", "html, body {width:100%;height:100%}"),
  leafletOutput("map", width = "100%", height = "100%"),
  absolutePanel(
    top = 10,
    right = 10,
    selectInput("colors", "Color Scheme",
                rownames(subset(
                  brewer.pal.info, category %in% c("seq", "div")
                )))
  )
)

server <- function(input, output, session) {
  output$map <- renderLeaflet({
    leaflet() %>% addProviderTiles(providers$CartoDB.Positron) %>% setView(-75.14, 40, zoom = 11)
  })
  
  observe({
    print(paste("colorscale: ", input$colors))
    leafletProxy("map", session) %>%
      clearShapes() %>%
      clearControls() %>%
      addGeoJSONChoropleth(
        "https://rawgit.com/TrantorM/leaflet-choropleth/gh-pages/examples/basic_topo/crimes_by_district.topojson",
        valueProperty = "incidents",
        scale = input$colors,
        mode = "q",
        steps = 5,
        color = "#ffffff",
        weight = 1,
        fillOpacity = 0.5,
        highlightOptions =
          highlightOptions(
            fillOpacity = 1,
            weight = 2,
            opacity = 1,
            color = "#000000",
            bringToFront = TRUE,
            sendToBack = TRUE
          ),
        legendOptions =
          legendOptions(title = "Crimes", position = "bottomright"),
      )
  })
}

shinyApp(ui, server)

[neon-ninja]

With this PR in place - https://github.com/bhaskarvk/leaflet-choropleth/pull/1/files#diff-1a04ef99957189d3dcef4a74278eddd33a16a2bbe9609aa53b65bf369831fd7f - there's a possible workaround, which is re-running renderLeaflet like so:

library(leaflet.extras)
library(shiny)
library(RColorBrewer)

ui <- bootstrapPage(
  tags$style(type = "text/css", "html, body {width:100%;height:100%}"),
  leafletOutput("map", width = "100%", height = "100%"),
  absolutePanel(
    top = 10,
    right = 10,
    selectInput("colors", "Color Scheme",
                rownames(subset(
                  brewer.pal.info, category %in% c("seq", "div")
                )))
  )
)

server <- function(input, output, session) {
  output$map <- renderLeaflet({
    leaflet() %>% addProviderTiles(providers$CartoDB.Positron) %>% setView(-75.14, 40, zoom = 11) %>%
      addGeoJSONChoropleth(
        "https://rawgit.com/TrantorM/leaflet-choropleth/gh-pages/examples/basic_topo/crimes_by_district.topojson",
        valueProperty = "incidents",
        scale = input$colors,
        mode = "q",
        steps = 5,
        color = "#ffffff",
        weight = 1,
        fillOpacity = 0.5,
        highlightOptions =
          highlightOptions(
            fillOpacity = 1,
            weight = 2,
            opacity = 1,
            color = "#000000",
            bringToFront = TRUE,
            sendToBack = TRUE
          ),
        legendOptions =
          legendOptions(title = "Crimes", position = "bottomright"),
      )
  })
}

shinyApp(ui, server)

[neon-ninja]

Setting layerId = "main", is another workaround that works with that PR

[neon-ninja]

Here's my build of this package with the fix btw https://github.com/neon-ninja/leaflet.extras