Leaflet for R: How to change default CSS cluster classes

Question

How do I change the default CSS classes which define cluster objects from within the Leaflet for R interface? For example, if I wanted to remove the opacity from the .marker

Answer 1

You can maybe try to add inline CSS to the different markers in the function that creates the icons, for ex:

clusterOptions = markerClusterOptions(iconCreateFunction=JS("function (cluster) {    
    var childCount = cluster.getChildCount();  
    if (childCount < 100) {  
      c = 'rgba(181, 226, 140, 1.0);'
    } else if (childCount < 1000) {  
      c = 'rgba(240, 194, 12, 1);'  
    } else { 
      c = 'rgba(241, 128, 23, 1);'  
    }    
    return new L.DivIcon({ html: '
' + childCount + '
', className: 'marker-cluster', iconSize: new L.Point(40, 40) });

  }")

If you are using shiny, you can also change the iconCreateFunction to assign a different class to each marker, and add tags$style in the header to set the CSS for these classes. Here's an example:

ui <- fluidPage(
  tags$head(tags$style(HTML("
  .marker-custom-small {
  background-color: rgba(181, 226, 140, 1);
    }
.marker-customr-small div {
    background-color: rgba(110, 204, 57, 1);
    }

.marker-custom-medium {
    background-color: rgba(241, 211, 87, 1);
    }
.marker-custom-medium div {
    background-color: rgba(240, 194, 12, 1);
    }

.marker-custom-large {
    background-color: rgba(253, 156, 115, 1);
    }
.marker-custom-large div {
    background-color: rgba(241, 128, 23, 1);
    }"))),
  leafletOutput("mymap"))

server<-function(input, output, session) {
  output$mymap <- renderLeaflet({
    leaflet(quakes) %>% addTiles() %>% addMarkers(
      clusterOptions = markerClusterOptions(iconCreateFunction=JS("function (cluster) {    
    var childCount = cluster.getChildCount(); 
    var c = ' marker-custom-';  
    if (childCount < 100) {  
      c += 'large';  
    } else if (childCount < 1000) {  
      c += 'medium';  
    } else { 
      c += 'small';  
    }    
    return new L.DivIcon({ html: '
' + childCount + '
', className: 'marker-cluster' + c, iconSize: new L.Point(40, 40) });

  }"))
    )
  })
}

shinyApp(ui,server)

Couldn't figure out how to have custom CSS in the leaflet outside of a shiny app.