使用R中的传单创建带有标记的虚假地图

Question

I would like to create a fake map with leafleat. The idea is to have a circle with center in 0,0 and radius 2 and show some markers inside. This is how I generate the circle (comments on how to improve the code are very welcome!)

library(sp)
library(leaflet)
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(0,0),5,npoints = 100)

I am able to draw the circle with the following code:

leaflet(height = "400px") %>% addPolygons(data = Circle.Town)

I would like to use the following data to add markers to my map:

df1 <- data.frame(long=c(0.6,1,1.4), lat=c(-2, -.8, -0.2), other=c('a', 'b', 'c'), Color=c(10,8,6), 
                  type=c('Public', 'Public', 'Private'), id=c(1:3))

I would like the color of the marker to be Color and the shape to be type . I would also like to have a tooltip that shows id and other when I hover the mouse over the marker.

I tried this:

leaflet(height = "400px") %>% addPolygons(data = Circle.Town) %>% addMarkers(data = df1, lat = lat, lng =long )

but I get an error:

Error in inherits(f, "formula") : object 'long' not found

Thanks for the help!

Answer 1

The columns in your data frame are expressed as formulas, and formulas start with a twiddle ~ :

  leaflet(height = "400px") %>% 
       addPolygons(data = Circle.Town) %>%
       addMarkers(data = df1, lat = ~lat, lng =~long )