leaflegend (version 1.2.1)

addLegendImage: Add a Legend with Images

Description

Creates a legend with images that are embedded into a 'leaflet' map so that images do not need to be packaged when saving a 'leaflet' map as HTML. Full control over the label and title style. The 'leaflet' map is passed through and the output is a control so that legend is fully integrated with other functionalities.

Usage

addLegendImage(
  map,
  images,
  labels,
  title = NULL,
  labelStyle = "font-size: 24px; vertical-align: middle;",
  orientation = c("vertical", "horizontal"),
  width = 20,
  height = 20,
  group = NULL,
  className = "info legend leaflet-control",
  ...
)

Value

an object from addControl

Arguments

map

a map widget object created from 'leaflet'

images

path to the image file

labels

labels for each image

title

the legend title, pass in HTML to style

labelStyle

character string of style argument for HTML text

orientation

stack the legend items vertically or horizontally

width

in pixels

height

in pixels

group

group name of a leaflet layer group

className

extra CSS class to append to the control, space separated

...

arguments to pass to addControl

Examples

library(leaflet)
data(quakes)

quakes1 <- quakes[1:10,]

colors <- c('blue', 'red', 'yellow', 'green', 'orange', 'purple')
i <- as.integer(cut(quakes$mag, breaks = quantile(quakes$mag, seq(0,1,1/6)),
                    include.lowest = TRUE))
leafImg <- system.file(sprintf('img/leaf-%s.png', colors),
                       package = 'leaflegend')
leafIcons <- icons(
  iconUrl = leafImg[i],
  iconWidth = 133/236 * 50, iconHeight = 50
)
leaflet(data = quakes) %>% addTiles() %>%
  addMarkers(~long, ~lat, icon = leafIcons) %>%
  addLegendImage(images = leafImg,
                 labels = colors,
                 width = 133/236 * 50,
                 height = 50,
                 orientation = 'vertical',
                 title = htmltools::tags$div('Leaf',
                                             style = 'font-size: 24px;
                                             text-align: center;'),
                 position = 'topright')

 # use raster images with size encodings
 height <- sizeNumeric(quakes$depth, baseSize = 40)
 width <- height * 38 / 95
 symbols <- icons(
   iconUrl = leafImg[4],
   iconWidth = width,
   iconHeight = height)
 probs <- c(.2, .4, .6, .8)
 leaflet(quakes) %>%
   addTiles() %>%
   addMarkers(icon = symbols,
              lat = ~lat, lng = ~long) %>%
   addLegendImage(
     images = rep(leafImg[4], 4),
     labels = round(quantile(height, probs = probs), 0),
     width = quantile(height, probs = probs) * 38 / 95,
     height = quantile(height, probs = probs),
     title = htmltools::tags$div(
       'Leaf',
       style = 'font-size: 24px; text-align: center; margin-bottom: 5px;'),
     position = 'topright', orientation = 'vertical')