Use leaflet control widget

leaflet is a R package allowing to build interactive maps. This post follows the leaflet introduction and explain how to build a bubble map.

The input required to build such a map is a list of GPS coordinates, with a numeric value attributed to each location to control the bubble size and color.

Markers are added using the addCircleMarkers() function, and bubble color is mapped to a color scale build with binning.

# Load libraries
library(leaflet)

# Make data with several positions
data_red <- data.frame(LONG=42+rnorm(10), LAT=23+rnorm(10), PLACE=paste("Red_place_",seq(1,10)))
data_blue <- data.frame(LONG=42+rnorm(10), LAT=23+rnorm(10), PLACE=paste("Blue_place_",seq(1,10)))

# Initialize the leaflet map:
m <- leaflet() %>% 
  setView(lng=42, lat=23, zoom=6 ) %>%

  # Add two tiles
  addProviderTiles("Esri.WorldImagery", group="background 1") %>%
  addTiles(options = providerTileOptions(noWrap = TRUE), group="background 2") %>%

  # Add 2 marker groups
  addCircleMarkers(data=data_red, lng=~LONG , lat=~LAT, radius=8 , color="black",
                   fillColor="red", stroke = TRUE, fillOpacity = 0.8, group="Red") %>%
  addCircleMarkers(data=data_blue, lng=~LONG , lat=~LAT, radius=8 , color="black",
                   fillColor="blue", stroke = TRUE, fillOpacity = 0.8, group="Blue") %>%

  # Add the control widget
  addLayersControl(overlayGroups = c("Red","Blue") , baseGroups = c("background 1","background 2"), 
                   options = layersControlOptions(collapsed = FALSE))

m

# save the widget in a html file if needed.
# library(htmlwidgets)
# saveWidget(m, file=paste0( getwd(), "/HtmlWidget/bubblemapControl.html"))