This post explains how to build a
bubble map with R and the
leaflet
package. It shows a set of earthquakes and
their intensity in the Pacific Ocean.
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"))