Add different legends in different layers on leaflet map in R

Question

library(leaflet)
library(htmltools)
library(htmlwidgets)
library(dplyr)
#
df1 <- data.frame(points=c("p1", "p2"), lat=c(49.47259, 49.48095), long=c(-103.7054, -103.6126), value=c(50.34, 100.25))
df2 <- data.frame(points=c("p1", "p2"), lat=c(49.47809, 49.66849), long=c(-103.5614, -103.0224), value=c(300.56, 505.34))
#
pal1 <- colorNumeric(
palette = "PRGn",
domain = df1$value
)
#
pal2 <- colorNumeric(
palette = "PRGn",
domain = df2$value
)
#
n <- leaflet() %>% addTiles(group="1st layer") %>% addTiles(group="2nd layer") %>%
addCircles(data=df1, lng=~long, lat=~lat, weight = 3, radius=250, color = ~pal1(value),
         stroke = TRUE, fillOpacity = 0.8,group="1st layer") %>%
addCircles(data=df2, lng=~long, lat=~lat, weight = 3, radius=250, color = ~pal2(value),
         stroke = TRUE, fillOpacity = 0.8,group="2nd layer") %>%
addLegend("bottomright", pal = pal1, values = df1$value, title = "legend_df1") %>%
addLegend("topright", pal = pal2, values = df2$value, title = "legend_df2") %>%
addLayersControl(baseGroups=c("1st layer","2nd layer"),
               options=layersControlOptions(collapsed = F))
n

I want that when I click on "1st layer" then only "legend_df1" will appear and when I click on "2nd layer" then only "legend_df2" will appear and "legend_df1" will be vanished. Therefore, in each layer different legends will appear, not both legends together. Can anybody please help me out?

Answer 1

This is now possible with overlayGroups

library(leaflet)

df1 <- data.frame(points=c("p1", "p2"), lat=c(49.47259, 49.48095), long=c(-103.7054, -103.6126), value=c(50.34, 100.25))
df2 <- data.frame(points=c("p1", "p2"), lat=c(49.47809, 49.66849), long=c(-103.5614, -103.0224), value=c(300.56, 505.34))

pal1 <- colorNumeric(
  palette = "inferno",
  domain = df1$value
)

pal2 <- colorNumeric(
  palette = "viridis",
  domain = df2$value
)

leaflet() %>% 
  addProviderTiles(providers$CartoDB.DarkMatter) %>% 
  addCircleMarkers(data=df1, lng=~long, lat=~lat, 
                   color = ~pal1(value),
                   group="group_1") %>%
  addCircleMarkers(data=df2, lng=~long, lat=~lat, 
                   color = ~pal2(value),
                   group="group_2") %>%
  addLegend("bottomright", pal = pal1, title="grp1",
            values = df1$value, group="group_1") %>%
  addLegend("bottomright", pal = pal2, title="grp2",
            values = df2$value, group="group_2") %>%
  addLayersControl(overlayGroups = c("group_1","group_2"),
                   options = layersControlOptions(collapsed = FALSE))