Grouped layer control in Leaflet R - r

Question

There is a plug-in for Leaflet JS that allows to group the layers in the layer control. https://github.com/ismyrnow/Leaflet.groupedlayercontrol
This plug-in does not seem to exist for Leaflet R but I found this post saying that there is a way to use arbitraty Leaflet JS plug-in in Leaflet R.
https://gist.github.com/jcheng5/c084a59717f18e947a17955007dc5f92
I tried to apply this method to the Leaflet.groupedlayercontrol plug-in but did not succeed. Do you have any idea how I can possibly use this plug-in or any other way to group my layers in the layercontrol generated by Leaflet R? Thank you.

Answer 1

You definitely can do layer control in leafletR. If you version does not have it, then you need to update, probably from the most recent GITHUB version.
I am working on a map right now that has layer controls, see the photograph. Here is the code that makes it happen. As you can see each of the addPolygons has a group = " A Name" This is where you identify the layers in the check boxes on my image.
map<-leaflet()%>%
addTiles()%>%
addPolygons(data = plotMerge,
fillColor = ~pal(plotMerge$incomePerCapita),
color = "#000000", #this is an outline color
fillOpacity = 0.8,
group="Tract",
weight = 0.2,
popup=popup)%>%
addPolygons(data = countyPoly,
fillColor = "transparent",
color = "#000000", #this is an outline color
fillOpacity = 0.8,
group="County",
popup=countyPoly#data$NAME,
weight = 2)%>%
addPolygons(data = townPoly,
fillColor = "transparent",
color = "#000000", #this is an outline color
fillOpacity = 0.8,
group="Town",
weight = .8,
popup=townPoly#data$TOWN)%>%
addPolygons(data = rphnPoly,
fillColor = "transparent",
color = "#000000", #this is an outline color
fillOpacity = 0.8,
group="Public Health Region",
weight = .8,
popup=rphnPoly#data$PHN)%>%
addLegend(pal = pal,
values = plotMerge$incomePerCapita,
position = "bottomright",
title = "State-wide Income Percentiles",
labFormat = labelFormat(digits=1))%>%
addLayersControl(
overlayGroups =c("County", "Town", "Public Health Region", "Tract"),
options = layersControlOptions(collapsed=FALSE)
)
saveWidget(map, file="map1.html", selfcontained=FALSE)
Here is what it looks like:
You can also add other controls check it out here:
Leaflet R Hidden Layers

Answer 2

I know this is an old question but I didn't find a good answer elsewhere - this may help others in the future.
Here is a reprex with comments that explains the code:
#load library
library(tidyverse)
library(leaflet)
#load data
data("quakes")
#map all points
# quakes %>%
# leaflet() %>%
# addProviderTiles(providers$CartoDB.Positron) %>%
# addCircleMarkers(lng = ~long, lat = ~lat, radius = 1)
#create a grouping variable -- this can be whatever you want to filter by
quakes <- quakes %>%
mutate(groups = case_when(
stations < 30 ~ 1,
stations < 50 ~ 2,
TRUE ~ 3
))
#function to plot a map with layer selection
map_layers <- function() {
#number of groups
k <- n_distinct(quakes$groups)
#base map
map <- leaflet() %>%
addProviderTiles(providers$CartoDB.Positron)
#loop through all groups and add a layer one at a time
for (i in 1:k) {
map <- map %>%
addCircleMarkers(
data = quakes %>% filter(groups == i), group = as.character(i),
lng = ~long, lat = ~lat, radius = 1
)
}
#create layer control
map %>%
addLayersControl(
overlayGroups = c(1:k),
options = layersControlOptions(collapsed = FALSE)) %>%
hideGroup(as.character(c(2:k))) #hide all groups except the 1st one
}
#plot the map
map_layers()