Create a list of icon data

An icon can be represented as a list of the form list(iconUrl, iconSize, ...). This function is vectorized over its arguments to create a list of icon data. Shorter argument values will be re-cycled. NULL values for these arguments will be ignored.

Usage

icons(
  iconUrl = NULL,
  iconRetinaUrl = NULL,
  iconWidth = NULL,
  iconHeight = NULL,
  iconAnchorX = NULL,
  iconAnchorY = NULL,
  shadowUrl = NULL,
  shadowRetinaUrl = NULL,
  shadowWidth = NULL,
  shadowHeight = NULL,
  shadowAnchorX = NULL,
  shadowAnchorY = NULL,
  popupAnchorX = NULL,
  popupAnchorY = NULL,
  className = NULL
)

Arguments

iconUrl

the URL or file path to the icon image

iconRetinaUrl

the URL or file path to a retina sized version of the icon image

iconWidth, iconHeight

size of the icon image in pixels

iconAnchorX, iconAnchorY

the coordinates of the "tip" of the icon (relative to its top left corner, i.e., the top left corner means iconAnchorX = 0 and iconAnchorY = 0), and the icon will be aligned so that this point is at the marker's geographical location

shadowUrl

the URL or file path to the icon shadow image

shadowRetinaUrl

the URL or file path to the retina sized version of the icon shadow image

shadowWidth, shadowHeight

size of the shadow image in pixels

shadowAnchorX, shadowAnchorY

the coordinates of the "tip" of the shadow

popupAnchorX, popupAnchorY

the coordinates of the point from which popups will "open", relative to the icon anchor

className

a custom class name to assign to both icon and shadow images

Value

A list of icon data that can be passed to the icon argument of addMarkers().

Examples

library(leaflet)

# adapted from https://leafletjs.com/examples/custom-icons.html

iconData <- data.frame(
  lat = c(rnorm(10, 0), rnorm(10, 1), rnorm(10, 2)),
  lng = c(rnorm(10, 0), rnorm(10, 3), rnorm(10, 6)),
  group = rep(sort(c("green", "red", "orange")), each = 10),
  stringsAsFactors = FALSE
)

leaflet() %>% addMarkers(
  data = iconData,
  icon = ~ icons(
    iconUrl = sprintf("https://leafletjs.com/examples/custom-icons/leaf-%s.png", group),
    shadowUrl = "https://leafletjs.com/examples/custom-icons/leaf-shadow.png",
    iconWidth = 38, iconHeight = 95, shadowWidth = 50, shadowHeight = 64,
    iconAnchorX = 22, iconAnchorY = 94, shadowAnchorX = 4, shadowAnchorY = 62,
    popupAnchorX = -3, popupAnchorY = -76
  )
)
#> Assuming "lng" and "lat" are longitude and latitude, respectively


# \donttest{

# use point symbols from base R graphics as icons
pchIcons <- function(pch = 0:14, width = 30, height = 30, ...) {
  n <- length(pch)
  files <- character(n)
  # create a sequence of png images
  for (i in seq_len(n)) {
    f <- tempfile(fileext = ".png")
    png(f, width = width, height = height, bg = "transparent")
    par(mar = c(0, 0, 0, 0))
    plot.new()
    points(.5, .5, pch = pch[i], cex = min(width, height) / 8, ...)
    dev.off()
    files[i] <- f
  }
  files
}

iconData <- matrix(rnorm(500), ncol = 2)
res <- kmeans(iconData, 10)
iconData <- cbind(iconData, res$cluster)
colnames(iconData) <- c("lat", "lng", "group")
iconData <- as.data.frame(iconData)

# 10 random point shapes for the 10 clusters in iconData
shapes <- sample(0:14, 10)
iconFiles <- pchIcons(shapes, 40, 40, col = "steelblue", lwd = 2)

# note the data has 250 rows, and there are 10 icons in iconFiles; they are
# connected by the `group` variable: the i-th row of iconData uses the
# group[i]-th icon in the icon list
leaflet() %>% addMarkers(
  data = iconData,
  icon = ~ icons(
    iconUrl = iconFiles[group],
    popupAnchorX = 20, popupAnchorY = 0
  ),
  popup = ~ sprintf(
    "lat = %.4f, long = %.4f, group = %s, pch = %s", lat, lng, group, shapes[group]
  )
)
#> Assuming "lng" and "lat" are longitude and latitude, respectively


unlink(iconFiles)  # clean up the tmp png files that have been embedded

# }