小叶闪亮的动态彩色多边形

Question

I am attempting to create an r shiny leaflet app that can dynamically color shade polygons with a pal spectrum depending on user input. Note I am not just coloring the polygons, I also want to use a color range to illustrate a range of values across a variable. (Hence the need for the pal spectrum)

The code below works fine - but the pal and fillColor inputs are not dynamic here.

output$mymap <- renderLeaflet({
map <- readShapeSpatial(paste(input$state,"Zip.shp",sep=""))

pal <- colorNumeric(
 palette = "YlGnBu",
 domain = map$college)

leaflet() %>%
addProviderTiles("CartoDB.Positron") %>%
addPolygons(data=map,
         fillColor=~pal(college),
fillOpacity = 0.7, 
 weight = 1, 
smoothFactor = 0.2)
 })}

But the version below fails. It creates a "no method for coercing this S4 class to a vector" Error. Why does this error occur and how can I fix this problem?

Code that fails:

 output$mymap <- renderLeaflet({

 map <- readShapeSpatial(paste(input$state,"Zip.shp",sep=""))

 pal <- colorNumeric(
  palette = "YlGnBu",
  domain = paste(map,"input$fill",sep=""))

leaflet() %>%
  addProviderTiles("CartoDB.Positron") %>%
  addPolygons(data=map,
              fillColor=~pal(input$fill),
              fillOpacity = 0.7, 
              weight = 1, 
              smoothFactor = 0.2)

Why can't I use the dynamic shiny input of input$fill to set the pal spectrum and fillColor for the Polygons? Any possible work arounds?

Thanks for any help!

Answer 1

I think your case can be solved by this suggestion . Hence you should use fillColor = ~pal()(input$fill) .