问题
Am I doing something wrong, or why does the below example not work? I am trying to make leaflet markercluster plugin work with leafletProxy() in an R Shiny app, using the option iconCreateFunction. Is the plugin not capable of adding customized icon markers to the map using leafletProxy()?
When I press the first button and zoom out in below example, I get an error saying:
TypeError: this._group.options.iconCreateFunction is not a function
I tried to copy the original example from the markercluster documentation:
library(shiny)
library(dplyr)
library(leaflet)
ui <- fluidPage(
titlePanel("Hello Shiny!"),
sidebarLayout(
sidebarPanel(
actionButton(inputId = "my_button1",
label = "Use leafletProxy()"),
actionButton(inputId = "my_button2",
label = "Use renderLeaflet()")
),
mainPanel(
leafletOutput(
outputId = "map",
width = "100%",
height = "300px"
)
)
)
)
server <- function(input, output, session) {
some_data <- data.frame(
"lon"=c(4.905167,4.906357,4.905831),
"lat"=c(52.37712,52.37783,52.37755),
"number_var"=c(5,9,7),
"name"=c("Jane","Harold","Mike"),
stringsAsFactors = F
)
output$map <- renderLeaflet({
return(
leaflet(data = some_data[0,]) %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
min(some_data$lon),
min(some_data$lat),
max(some_data$lon),
max(some_data$lat)
) %>%
addMarkers(
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = JS(paste0("function(cluster) {",
"return new L.DivIcon({",
"html: '<div style=\"background-color:rgba(77,77,77,0.5)\"><span>' + cluster.getChildCount() + '</div><span>',",
"className: 'marker-cluster'",
"});",
"}"))
)
)
)
})
observeEvent(input$my_button1,{
leafletProxy(mapId = "map",
session = session,
data = some_data) %>%
addProviderTiles(providers$CartoDB.Positron) %>%
clearMarkerClusters() %>%
clearMarkers() %>%
fitBounds(
min(some_data$lon),
min(some_data$lat),
max(some_data$lon),
max(some_data$lat)
) %>%
addMarkers(
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = JS(paste0("function(cluster) {",
"console.log('Here comes cluster',cluster); ",
"return new L.DivIcon({",
"html: '<div style=\"background-color:rgba(77,77,77,0.5)\"><span>' + cluster.getChildCount() + '</div><span>',",
"className: 'marker-cluster'",
"});",
"}"))
)
)
})
observeEvent(input$my_button2,{
output$map <- renderLeaflet({
leaflet(data = some_data) %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
min(some_data$lon),
min(some_data$lat),
max(some_data$lon),
max(some_data$lat)
) %>%
addMarkers(
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = JS(paste0("function(cluster) {",
"console.log('Here comes cluster',cluster); ",
"return new L.DivIcon({",
"html: '<div style=\"background-color:rgba(77,77,77,0.5)\"><span>' + cluster.getChildCount() + '</div><span>',",
"className: 'marker-cluster'",
"});",
"}"))
)
)
})
})
}
shinyApp(ui = ui, server = server)
Package versions:
dplyr_0.7.4
leaflet_1.1.0
shiny_1.0.5
R version 3.4.3 (2017-11-30)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.3 LTS
Browser version: Firefox Quantum 57.0.1 (64-bit)
回答1:
Revised solution
The behaviour of iconCreateFunction is definitely flakey when used within leafletProxy. Although I think there is caching in some browsers making it difficult to track visually.
In order to eliminate the javascript error you were experiencing, it is important to apply layerId and clusterId values as well as using removeMarker in lieu of clearMarkers.
N.B. A strange side-effect of my solution is that a marker is dropped when re-drawn, I'm getting a bit tired and will have another look later. That problem may or may not be trivial.
app.R
library(shiny)
library(dplyr)
library(leaflet)
ui <- fluidPage(
titlePanel("Hello Shiny!"),
sidebarLayout(
sidebarPanel(
actionButton(inputId = "my_button1",
label = "Use leafletProxy()"),
actionButton(inputId = "my_button2",
label = "Use renderLeaflet()")
),
mainPanel(
leafletOutput(
outputId = "mymap",
width = "100%",
height = "300px"
))
))
server <- function(input, output, session) {
some_data <- data.frame(
lon = c(4.905167, 4.906357, 4.905831),
lat = c(52.37712, 52.37783, 52.37755),
number_var = c(5, 9, 7),
name = c("Jane", "Harold", "Mike"),
stringsAsFactors = FALSE
)
marker_js <- JS("function(cluster) {
var html = '<div style=\"background-color:rgba(77,77,77,0.5)\"><span>' + cluster.getChildCount() + '</div><span>'
return new L.DivIcon({html: html, className: 'marker-cluster'});
}")
output$mymap <- renderLeaflet({
leaflet(some_data) %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
~min(lon),
~min(lat),
~max(lon),
~max(lat)
) %>%
addMarkers(
layerId = "mylayer",
clusterId = "mycluster",
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = marker_js
)
)
})
observeEvent(input$my_button1, {
leafletProxy("mymap", data = some_data) %>%
removeMarker(layerId = "mylayer") %>%
clearTiles %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
~min(lon),
~min(lat),
~max(lon),
~max(lat)
) %>%
addMarkers(
layerId = "mylayer",
clusterId = "mycluster",
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = marker_js
)
)
})
observeEvent(input$my_button2,{
output$mymap <- renderLeaflet({
leaflet(some_data) %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
~min(lon),
~min(lat),
~max(lon),
~max(lat)
) %>%
addMarkers(
layerId = "mylayer",
clusterId = "mycluster",
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = marker_js
)
)
})
})
}
shinyApp(ui = ui, server = server)
in-browser
No other javascript errors were noted.
回答2:
To follow Kevin's answer, modifying the clusterId to a vector gets the leafletProxy version to work for me. Not sure if this causes unintended consequences though...
app.R
library(shiny)
library(dplyr)
library(leaflet)
ui <- fluidPage(
titlePanel("Hello Shiny!"),
sidebarLayout(
sidebarPanel(
actionButton(inputId = "my_button1",
label = "Use leafletProxy()"),
actionButton(inputId = "my_button2",
label = "Use renderLeaflet()")
),
mainPanel(
leafletOutput(
outputId = "mymap",
width = "100%",
height = "300px"
))
))
server <- function(input, output, session) {
some_data <- data.frame(
lon = c(4.905167, 4.906357, 4.905831),
lat = c(52.37712, 52.37783, 52.37755),
number_var = c(5, 9, 7),
name = c("Jane", "Harold", "Mike"),
stringsAsFactors = FALSE
)
marker_js <- JS("function(cluster) {
var html = '<div style=\"background-color:rgba(77,77,77,0.5)\"><span>' + cluster.getChildCount() + '</div><span>'
return new L.DivIcon({html: html, className: 'marker-cluster'});
}")
output$mymap <- renderLeaflet({
leaflet(some_data) %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
~min(lon),
~min(lat),
~max(lon),
~max(lat)
) %>%
addMarkers(
layerId = "mylayer",
clusterId = "mycluster",
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = marker_js
)
)
})
observeEvent(input$my_button1, {
leafletProxy("mymap", data = some_data) %>%
removeMarker(layerId = "mylayer") %>%
clearTiles %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
~min(lon),
~min(lat),
~max(lon),
~max(lat)
) %>%
addMarkers(
layerId = "mylayer",
clusterId = ~name,
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = marker_js
)
)
})
observeEvent(input$my_button2,{
output$mymap <- renderLeaflet({
leaflet(some_data) %>%
addProviderTiles(providers$CartoDB.Positron) %>%
fitBounds(
~min(lon),
~min(lat),
~max(lon),
~max(lat)
) %>%
addMarkers(
layerId = "mylayer",
clusterId = "mycluster",
lng = ~lon,
lat = ~lat,
clusterOptions = markerClusterOptions(
iconCreateFunction = marker_js
)
)
})
})
}
shinyApp(ui = ui, server = server)
来源：https://stackoverflow.com/questions/47922951/does-markercluster-work-together-with-leafletproxy-and-option-iconcreatefuncti