Leaflet choropleth maps in shiny - unable to use addPolygons function properly - r

Question

I am new to writing shiny apps and new to using the leaflet package. I am trying to create a shiny app which will get user inputs and plot a choropleth map based on the aggregated values of the selected user variable.
My sample dataset has the following variables: statename latitude longitude countyname medianage asianpopulation otherpopulation
My app would ask the user to select from either username or countyname. Based on this selection, internally I group my dataset using statename or countyname.
Then the user selects either one or many from the variables: medianage asianpopulation otherpopulation.
Based on this, I want to plot the choropleth map on the sum of the values of these variables and show a table below with these values.
I am not able to use the addPolygons method to plot the map. Do I need to use a shape file for this? Where am I going wrong in this code?
library(dplyr)
library(shiny)
library(readr)
library(leaflet)
library(lazyeval)
library(rgdal)
setwd("E:/Data")
ui <- fluidPage(
titlePanel("Filters"),
sidebarLayout(
sidebarPanel(
radioButtons("level", "Select the Level", choices = c("State", "County"),selected = "State" ,inline = TRUE),
selectInput("variable", "Variable Name", choices = NULL, multiple = FALSE, selectize = TRUE, selected = "medianage")
),
mainPanel(
leafletOutput("map"),
dataTableOutput("heatmapdata")
)
)
)
server <- function(input, output, session) {
read_csv(file="Sample.csv") %>%
select(statename, latitude, longitude, countyname, medianage, asianpopulation, otherpopulation) -> heatmapData -> hd
variable = c()
group = c()
heatmapData <- data.frame(heatmapData)
hd <- heatmapData
heatmapdata_1 <- select(heatmapData, -c(latitude, longitude))
heatmapdata_2 <- select(heatmapdata_1, -c(statename, countyname))
updateSelectInput(session, "variable", choices = sort(unique(colnames(heatmapData))), selected = "medianage")
heatmapdata_2 <- heatmapdata_1
datasetLevel.group <- function(df, grp.var) {
df %>% group_by_(grp.var) %>%
summarise_each(funs(sum)) -> df
df
}
datasetLevel <- reactive({
heatmapdata_2 <- heatmapdata_1
inputvariable <- c("medianage")
if (input$level == "State") {
inputlevel = c("statename")
heatmapdata_2 <- select(heatmapdata_2, -c(countyname))
}
if (input$level == "County") {
inputlevel = c("countyname")
heatmapdata_2 <- select(heatmapdata_2, -c(statename))
}
sm <- datasetLevel.group(heatmapdata_2, inputlevel)
group <- inputlevel
variable <- inputvariable
l_hd <- list(sm, inputlevel, input$variable)
l_hd
})
output$map <- renderLeaflet(
{
leaflet() %>% addTiles(options=tileOptions(minZoom = 3, maxZoom = 10)) %>%
setView(lng = -98.35, lat = 39.5, zoom = 4) %>%
setMaxBounds( -180, 5, -52, 73)
}
)
output$heatmapdata <- renderDataTable(
select_(datasetLevel()[[1]], datasetLevel()[[2]], datasetLevel()[[3]]),
options = list(pageLength=5,
scrollX=TRUE,
lengthMenu = c(5, 10, 25, 100),
searching=FALSE)
)
observe({
pal <- colorQuantile("YlOrRd", NULL, n = 20)
leafletProxy("map", data = datasetLevel()[[1]]) %>%
clearMarkers() %>%
clearMarkerClusters() #%>%
# addPolygons(data = datasetLevel()[[1]],
# fillColor = ~pal(variable),
# fillOpacity = 0.8,
# color = "#BDBDC3",
# weight = 1)
})
}
shinyApp(ui = ui, server = server)
I have commented out the addPolygons code as I get an error with that. I have been breaking my head to get the maps color coded based on the aggregated values of the selected variable.
The data file can be found at: https://drive.google.com/file/d/0B4PQcgewfQ3-MF9lNjU4clpUcUk/view?usp=sharing
Any help on this will be really helpful. Thanks.