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Create a Leaflet map widget

Source: R/leaflet.R
leaflet.Rd

This function creates a Leaflet map widget using htmlwidgets. The widget can be rendered on HTML pages generated from R Markdown, Shiny, or other applications.

Usage

leaflet(
  data = NULL,
  width = NULL,
  height = NULL,
  padding = 0,
  options = leafletOptions(),
  elementId = NULL,
  sizingPolicy = leafletSizingPolicy(padding = padding)
)

leafletOptions(
  minZoom = NULL,
  maxZoom = NULL,
  crs = leafletCRS(),
  worldCopyJump = NULL,
  preferCanvas = NULL,
  ...
)

leafletCRS(
  crsClass = "L.CRS.EPSG3857",
  code = NULL,
  proj4def = NULL,
  projectedBounds = NULL,
  origin = NULL,
  transformation = NULL,
  scales = NULL,
  resolutions = NULL,
  bounds = NULL,
  tileSize = NULL
)

Arguments

data

a data object. Currently supported objects are matrix, data frame, spatial data from the sf package, SpatVector from the terra package, and the Spatial* objects from the sp package that represent points, lines, or polygons.

width

the width of the map

height

the height of the map

padding

the padding of the map

options

the map options

elementId

Use an explicit element ID for the widget (rather than an automatically generated one).

sizingPolicy

htmlwidgets sizing policy object. Defaults to leafletSizingPolicy()

minZoom

Minimum zoom level of the map. Overrides any minZoom set on map layers.

maxZoom

Maximum zoom level of the map. This overrides any maxZoom set on map layers.

crs

Coordinate Reference System to use. Don't change this if you're not sure what it means.

worldCopyJump

With this option enabled, the map tracks when you pan to another "copy" of the world and seamlessly jumps to the original one so that all overlays like markers and vector layers are still visible.

preferCanvas

Whether leaflet.js Paths should be rendered on a Canvas renderer.

...

other options used for leaflet.js map creation.

crsClass

One of L.CRS.EPSG3857, L.CRS.EPSG4326, L.CRS.EPSG3395, L.CRS.Simple, L.Proj.CRS

code

CRS identifier

proj4def

Proj4 string

projectedBounds

DEPRECATED! Use the bounds argument.

origin

Origin in projected coordinates, if set overrides transformation option.

transformation

to use when transforming projected coordinates into pixel coordinates

scales

Scale factors (pixels per projection unit, for example pixels/meter) for zoom levels; specify either scales or resolutions, not both

resolutions

factors (projection units per pixel, for example meters/pixel) for zoom levels; specify either scales or resolutions, not both

bounds

Bounds of the CRS, in projected coordinates; if defined, Proj4Leaflet will use this in the getSize method, otherwise defaulting to Leaflet's default CRS size

tileSize

DEPRECATED! Specify the tilesize in the tileOptions() argument.

Value

A HTML widget object, on which we can add graphics layers using %>% (see examples).

Details

The data argument is only needed if you are going to reference variables in this object later in map layers. For example, data can be a data frame containing columns latitude and longtitude, then we may add a circle layer to the map by leaflet(data) %>% addCircles(lat = ~latitude, lng = ~longtitude), where the variables in the formulae will be evaluated in the data.

Functions

  • leafletOptions(): Options for map creation

  • leafletCRS(): class to create a custom CRS

See also

leafletCRS() for creating a custom CRS.

See https://web.archive.org/web/20220702182250/https://leafletjs.com/reference-1.3.4.html#map-option for details and more options.

Examples

# !formatR
library(leaflet)
m <- leaflet() %>% addTiles()
m  # a map with the default OSM tile layer



# \donttest{
# set bounds
m %>% fitBounds(0, 40, 10, 50)



# move the center to Snedecor Hall
m <- m %>% setView(-93.65, 42.0285, zoom = 17)
m



# popup
m %>% addPopups(-93.65, 42.0285, "Here is the <b>Department of Statistics</b>, ISU")


rand_lng <- function(n = 10) rnorm(n, -93.65, .01)
rand_lat <- function(n = 10) rnorm(n, 42.0285, .01)

# use automatic bounds derived from lng/lat data
m <- m %>% clearBounds()

# popup
m %>% addPopups(rand_lng(), rand_lat(), "Random popups")



# marker
m %>% addMarkers(rand_lng(), rand_lat())


m %>% addMarkers(
  rand_lng(), rand_lat(), popup = paste("A random letter", sample(LETTERS, 10))
)



Rlogo <- file.path(R.home("doc"), "html", "logo.jpg")
m %>% addMarkers(
  174.7690922, -36.8523071, icon = list(
    iconUrl = Rlogo, iconSize = c(100, 76)
  ), popup = "R was born here!"
)



m %>% addMarkers(rnorm(30, 175), rnorm(30, -37), icon = list(
  iconUrl = Rlogo, iconSize = c(25, 19)
))



# circle (units in metres)
m %>% addCircles(rand_lng(50), rand_lat(50), radius = runif(50, 50, 150))



# circle marker (units in pixels)
m %>% addCircleMarkers(rand_lng(50), rand_lat(50), color = "#ff0000")


m %>% addCircleMarkers(rand_lng(100), rand_lat(100), radius = runif(100, 5, 15))



# rectangle
m %>% addRectangles(
  rand_lng(), rand_lat(), rand_lng(), rand_lat(),
  color = "red", fill = FALSE, dashArray = "5,5", weight = 3
)



# polyline
m %>% addPolylines(rand_lng(50), rand_lat(50))



# polygon
m %>% addPolygons(rand_lng(), rand_lat(), layerId = "foo")



# geoJSON
seattle_geojson <- list(
  type = "Feature",
  geometry = list(
    type = "MultiPolygon",
    coordinates = list(list(list(
      c(-122.36075812146,  47.6759920119894),
      c(-122.360781646764, 47.6668890126755),
      c(-122.360782108665,  47.6614990696722),
      c(-122.366199035722, 47.6614990696722),
      c(-122.366199035722,  47.6592874248973),
      c(-122.364582509469, 47.6576254522105),
      c(-122.363887331445,  47.6569107302038),
      c(-122.360865528129, 47.6538418253251),
      c(-122.360866157644,  47.6535254473167),
      c(-122.360866581103, 47.6533126275176),
      c(-122.362526540691,  47.6541872926348),
      c(-122.364442114483, 47.6551892850798),
      c(-122.366077719797,  47.6560733960606),
      c(-122.368818463838, 47.6579742346694),
      c(-122.370115159943,  47.6588730808334),
      c(-122.372295967029, 47.6604350102328),
      c(-122.37381369088,  47.660582362063),
      c(-122.375522972109, 47.6606413027949),
      c(-122.376079703095,  47.6608793094619),
      c(-122.376206315662, 47.6609242364243),
      c(-122.377610811371,  47.6606160735197),
      c(-122.379857378879, 47.6610306942278),
      c(-122.382454873022,  47.6627496239169),
      c(-122.385357955057, 47.6638573778241),
      c(-122.386007328104,  47.6640865692306),
      c(-122.387186331506, 47.6654326177161),
      c(-122.387802656231,  47.6661492860294),
      c(-122.388108244121, 47.6664548739202),
      c(-122.389177800763,  47.6663784774359),
      c(-122.390582858689, 47.6665072251861),
      c(-122.390793942299,  47.6659699214511),
      c(-122.391507906234, 47.6659200946229),
      c(-122.392883050767,  47.6664166747017),
      c(-122.392847210144, 47.6678696739431),
      c(-122.392904778401,  47.6709016021624),
      c(-122.39296705153, 47.6732047491624),
      c(-122.393000803496,  47.6759322346303),
      c(-122.37666945305, 47.6759896300663),
      c(-122.376486363943,  47.6759891899754),
      c(-122.366078869215, 47.6759641734893),
      c(-122.36075812146,  47.6759920119894)
    )))
  ),
  properties = list(
    name = "Ballard",
    population = 48000,
    # You can inline styles if you want
    style = list(
      fillColor = "yellow",
      weight = 2,
      color = "#000000"
    )
  ),
  id = "ballard"
)
m %>% setView(-122.36075812146, 47.6759920119894, zoom = 13) %>% addGeoJSON(seattle_geojson)




# use the Dark Matter layer from CartoDB
leaflet() %>% addTiles("https://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png",
  attribution = paste(
    "&copy; <a href=\"https://openstreetmap.org\">OpenStreetMap</a> contributors",
    "&copy; <a href=\"https://cartodb.com/attributions\">CartoDB</a>"
  )
) %>% setView(-122.36, 47.67, zoom = 10)



# provide a data frame to leaflet()
categories <- LETTERS[1:10]
df <- data.frame(
  lat = rand_lat(100), lng = rand_lng(100), size = runif(100, 5, 20),
  category = factor(sample(categories, 100, replace = TRUE), levels = categories),
  value = rnorm(100)
)
m <- leaflet(df) %>% addTiles()
m %>% addCircleMarkers(~lng, ~lat, radius = ~size)


m %>% addCircleMarkers(~lng, ~lat, radius = runif(100, 4, 10), color = c("red"))



# Discrete colors using the "RdYlBu" colorbrewer palette, mapped to categories
RdYlBu <- colorFactor("RdYlBu", domain = categories)
m %>% addCircleMarkers(~lng, ~lat, radius = ~size,
  color = ~RdYlBu(category), fillOpacity = 0.5)



# Continuous colors using the "Greens" colorbrewer palette, mapped to value
greens <- colorNumeric("Greens", domain = NULL)
m %>% addCircleMarkers(~lng, ~lat, radius = ~size,
  color = ~greens(value), fillOpacity = 0.5)



# }