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Introduction to leaflet

Source: vignettes/articles/leaflet.Rmd
leaflet.Rmd

Introduction

Leaflet is one of the most popular open-source JavaScript libraries for interactive maps. It’s used by websites ranging from The New York Times and The Washington Post to GitHub and Flickr, as well as GIS specialists like OpenStreetMap, Mapbox, and CartoDB.

This R package makes it easy to integrate and control Leaflet maps in R.

Features

  • Interactive panning/zooming
  • Compose maps using arbitrary combinations of:
    • Map tiles
    • Markers
    • Polygons
    • Lines
    • Popups
    • GeoJSON
  • Create maps right from the R console or RStudio
  • Embed maps in knitr/R Markdown/Quarto documents, and Shiny apps
  • Easily render spatial objects from the sf package, or data frames with latitude/longitude columns
  • Use map bounds and mouse events to drive Shiny logic
  • Display maps in non spherical Mercator projections
  • Augment map features using chosen plugins from leaflet plugins repository

Installation

To install this R package, run this command at your R prompt:

install.packages("leaflet")
# to install the development version from Github, run
# devtools::install_github("rstudio/leaflet")

Once installed, you can use this package at the R console, within R Markdown documents, and within Shiny applications.

Basic Usage

You create a Leaflet map with these basic steps:

  1. Create a map widget by calling leaflet().
  2. Add layers (i.e., features) to the map by using layer functions (e.g., addTiles, addMarkers, addPolygons) to modify the map widget.
  3. Repeat step 2 as desired.
  4. Print the map widget to display it.

Here’s a basic example:

library(leaflet)

m <- leaflet() %>%
  addTiles() %>%  # Add default OpenStreetMap map tiles
  addMarkers(lng=174.768, lat=-36.852, popup="The birthplace of R")
m  # Print the map

In case you’re not familiar with the pipe (magrittr or base) operator (%>% / |>), here is the equivalent without using pipes:

m <- leaflet()
m <- addTiles(m)
m <- addMarkers(m, lng=174.768, lat=-36.852, popup="The birthplace of R")
m

Next Steps

We highly recommend that you proceed to The Map Widget page before exploring the rest of this site, as it describes common idioms we’ll use throughout the examples on the other pages.

Although we have tried to provide an R-like interface to Leaflet, you may want to check out the API documentation of Leaflet occasionally when the meanings of certain parameters are not clear to you.