inst/examples/legend.R

In rstudio/leaflet: Create Interactive Web Maps with the JavaScript 'Leaflet' Library

# !formatR
library(leaflet)
# a manual legend
leaflet() %>% addTiles() %>% addLegend(
  position = "bottomright",
  colors = rgb(t(col2rgb(palette())) / 255),
  labels = palette(), opacity = 1,
  title = "An Obvious Legend"
)

\donttest{

# an automatic legend derived from the color palette
df <- local({
  n <- 300; x <- rnorm(n); y <- rnorm(n)
  z <- sqrt(x ^ 2 + y ^ 2); z[sample(n, 10)] <- NA
  data.frame(x, y, z)
})
pal <- colorNumeric("OrRd", df$z)
leaflet(df) %>%
  addTiles() %>%
  addCircleMarkers(~x, ~y, color = ~pal(z), group = "circles") %>%
  addLegend(pal = pal, values = ~z, group = "circles", position = "bottomleft") %>%
  addLayersControl(overlayGroups = c("circles"))

# format legend labels
df <- data.frame(x = rnorm(100), y = rexp(100, 2), z = runif(100))
pal <- colorBin("PuOr", df$z, bins = c(0, .1, .4, .9, 1))
leaflet(df) %>%
  addTiles() %>%
  addCircleMarkers(~x, ~y, color = ~pal(z), group = "circles") %>%
  addLegend(pal = pal, values = ~z, group = "circles", position = "bottomleft") %>%
  addLayersControl(overlayGroups = c("circles"))

leaflet(df) %>%
  addTiles() %>%
  addCircleMarkers(~x, ~y, color = ~pal(z), group = "circles") %>%
  addLegend(pal = pal, values = ~z, labFormat = labelFormat(
    prefix = "(", suffix = ")%", between = ", ",
    transform = function(x) 100 * x
  ),  group = "circles", position = "bottomleft" ) %>%
  addLayersControl(overlayGroups = c("circles"))
}