Popup when hover with leaflet in R?

Question

My leaflet map looks something like this:

library(sp)
library(leaflet)
circleFun <- function(center = c(0,0),diameter = 1, npoints = 100){
  r = diameter / 2
         


        

Answer 1

Here is an alternative:

library(leaflet)
library(htmltools)
library(htmlwidgets)

yourmap <- leaflet(height = "400px") %>% 
  addTiles() %>%
  addPolygons(data = Circle.Town, color = 'green',  fillOpacity = .7) %>%
  addCircleMarkers(data = df1, lat = ~lat, lng =~long, 
                   radius = ~VAM, popup = ~as.character(X), 
                   fillColor = ~pal(VAM),
                   stroke = FALSE, fillOpacity = 0.8,
                   clusterOptions = markerClusterOptions()) %>% 
  addLegend(position = "topright",
            pal = pal, values = df1$VAM,
            title = "VAM",
            opacity = 1
  ) %>% 
  setView(lng = 1, lat = -1, zoom = 8)

setwd("~/Desktop/")
saveWidget(yourmap, file="yourmap.html")

In your desktop, you will have an html and a folder saved under yourmap. Open the leaflet.js file located in /pathTo/yourmap_files/leaflet-binding-1.0.1.9002. In leaflet.js, scroll down to var popup = df.get(i, 'popup'); and paste just below:

          marker.on('mouseover', function (e) {
    this.openPopup();
});
marker.on('mouseout', function (e) {
    this.closePopup();
});

Save and reopen yourmap.html file. Hover on one of your point!!

Answer 2

This may have been added to the leaflet package since this question was posed a year ago, but this can be done via the label argument. I am using leaflet R package version 1.1.0.

Read the data in as above:

library(sp)
library(leaflet)
library(dplyr)

circleFun <- function(center = c(0,0),diameter = 1, npoints = 100){
  r = diameter / 2
  tt <- seq(0,2*pi,length.out = npoints)
  xx <- center[1] + r * cos(tt)
  yy <- center[2] + r * sin(tt)
  Sr1 = Polygon(cbind(xx, yy))
  Srs1 = Polygons(list(Sr1), "s1")
  SpP = SpatialPolygons(list(Srs1), 1:1)
  return(SpP)
}
Circle.Town <- circleFun(c(1,-1),2.3,npoints = 100)

df1 <- data.frame(long=c(0.6,1,1.4), lat=c(-2, -.8, -0.2), other=c('a', 'b', 'c'), VAM=c(10,8,6), 
  type=c('Public', 'Public', 'Private'), id=c(1:3)) %>% 
  mutate(X=paste0('<strong>id: </strong>', 
    id,
    '<br><strong>type</strong>: ',
    type,
    '<br><strong>VAM</strong>: ',
    VAM))

# Create a continuous palette function
pal <- colorNumeric(
  palette = "RdYlBu",
  domain = df1$VAM
)

But create a list of labels instead of vector:

labs <- as.list(df1$X)

And then lapply the HTML function over that list within the label argument. Note to use label instead of popup.

library(htmltools)
leaflet(height = "400px") %>% 
  addTiles() %>%
  addPolygons(data = Circle.Town, color = 'green',  fillOpacity = .7) %>%
  addCircleMarkers(data = df1, lat = ~lat, lng =~long, 
    radius = ~VAM, label = lapply(labs, HTML), 
    fillColor = ~pal(VAM),
    stroke = FALSE, fillOpacity = 0.8,
    clusterOptions = markerClusterOptions()) %>% 
  addLegend(position = "topright",
    pal = pal, values = df1$VAM,
    title = "VAM",
    opacity = 1
  ) %>% 
  setView(lng = 1, lat = -1, zoom = 8)

This method is described in an an answer to this SO question: R and Leaflet: How to arrange label text across multiple lines

There is more info on HTML in labels in leaflet documentation: https://rstudio.github.io/leaflet/popups.html