R, GeoJSON and the Flyer

Question

I recently learned about leafletjs.com with the message R-Bloggers.com. One such tutorial that I would like to achieve is to create interactive choropleth maps with a flyer ( http://leafletjs.com/examples/choropleth.html ). I am using the rjson package for R to create a data.js file for reading booklets. Although I had success using the provided form file as a readable JSON file in the leaflet, I cannot repeat this process when trying to combine additional properties from the data frame ("data.csv") into a JSON file; in this case, I did rGIS to attach the data on the number of cans in each school listed in the data frame. What I would like to get is to create a horopleth map in a leaflet that displays the high school district (as defined by the NAME variable) and the sum of the "cans". I believe the problem is that writeOGR exports information as points, not a polygon?

{ "type": "Feature", "properties": { "name": "Alabama", "density": 94.65 }, "geometry": ... ... } ###load R scripts from dropbox dropbox.eval <- function(x, noeval=F) { require(RCurl) intext <- getURL(paste0("https://dl.dropboxusercontent.com/",x), ssl.verifypeer = FALSE) intext <- gsub("\r","", intext) if (!noeval) eval(parse(text = intext), envir= .GlobalEnv) return(intext) } ##pull scripts from dropbox dropbox.eval("s/wgb3vtd9qfc9br9/pkg.load.r") dropbox.eval("s/tf4ni48hf6oh2ou/dropbox.r") ##load packages pkg.load(c(ggplot2,plyr,gdata,sp,maptools,rgdal,reshape2,rjson)) ###setup data frames dl_from_dropbox("data.csv","dx3qrcexmi9kagx") data<-read.csv(file='data.csv',header=TRUE) ###prepare GIS shape and data for plotting dropbox.eval("s/y2jsx3dditjucxu/dlshape.r") temp <- tempfile() dlshape(shploc="http://files.hawaii.gov/dbedt/op/gis/data/highdist_n83.shp.zip", temp) shape<- readOGR(".","highdist_n83") #HDOE high school districts shape@proj4string shape2<- spTransform(shape, CRS("+proj=longlat +datum=NAD83")) data.2<-ddply(data, .(year, schoolcode, longitude, latitude,NAME,HDist,SDist), summarise, total = sum(total), cans= sum(cans)) ###merging back shape properties and data frame coordinates(data.2) <-~longitude + latitude shape2@data $id <- rownames( shape2@data ) sh.df <- as.data.frame(shape2) sh.fort <- fortify(shape2 , region = "id" ) sh.line<- join(sh.fort, sh.df , by = "id" ) mapdf <- merge( sh.line , data.2 , by.x= "NAME", by.y="NAME" , all=TRUE) mapdf <- mapdf[ order( mapdf$order ) , ] ###exporting merged data frame as JSON mapdf.sp <- mapdf coordinates(mapdf.sp) <- c("long", "lat") writeOGR(mapdf.sp, "hssra.geojson","mapdf", driver = "GeoJSON") 

However, it seems my functions are constantly repeating. How can I aggregate function information so that it looks like this:

 var statesData = {"type":"FeatureCollection","features":[ {"type":"Feature","id":"01","properties":{"name":"Alabama","density":94.65}, "geometry":{"type":"Polygon","coordinates":[[[-87.359296,35.00118], [-85.606675,34.984749],[-85.431413,34.124869],[-85.184951,32.859696], [-85.069935,32.580372],[-84.960397,32.421541],[-85.004212,32.322956], [-84.889196,32.262709],[-85.058981,32.13674],[-85.053504,32.01077],[-85.141136,31.840985], [-85.042551,31.539753],[-85.113751,31.27686],[-85.004212,31.003013],[-85.497137,30.997536], [-87.600282,30.997536],[-87.633143,30.86609],[-87.408589,30.674397],[-87.446927,30.510088], [-87.37025,30.427934],[-87.518128,30.280057],[-87.655051,30.247195],[-87.90699,30.411504], [-87.934375,30.657966],[-88.011052,30.685351],[-88.10416,30.499135],[-88.137022,30.318396], [-88.394438,30.367688],[-88.471115,31.895754],[-88.241084,33.796253], [-88.098683,34.891641],[-88.202745,34.995703],[-87.359296,35.00118]]]}}, {"type":"Feature","id":"02","properties":{"name":"Alaska","density":1.264}, "geometry":{"type":"MultiPolygon","coordinates":[[[[-131.602021,55.117982], [-131.569159,55.28229],[-131.355558,55.183705],[-131.38842,55.01392], [-131.645836,55.035827],[-131.602021,55.117982]]],[[[-131.832052,55.42469], [-131.645836,55.304197],[-131.749898,55.128935],[-131.832052,55.189182], [-131.832052,55.42469]]],[[[-132.976733,56.437924],[-132.735747,56.459832], [-132.631685,56.421493],[-132.664547,56.273616],[-132.878148,56.240754], [-133.069841,56.333862],[-132.976733,56.437924]]],[[[-133.595627,56.350293], 

Answer 1

I decided to resolve this issue.

What I basically did was basically insert data.2 df into the form file: ( shape2@data <-join( shape2@data ,data.2)

and then using the rgdal package to write OGR in JSON format (using the JSON driver) with the extension * .js.

I hope this helps others.