I am finding some methods that can provide simple output.

I found a useful method [StandardDistance_stats][1] in ARCGIS, but the result is not what i am looking for, I only need the result of a lat/lng point and the size of the circle in number form, so I can plot it to my web map.

[![enter image description here][2]][2]

Now I am using geomean in geosphere package, it gives the mean of lat/lng points but still missing the size of the circle. 

Edit: I found a solution for it, but I am stuck in import R script into Java 
    
    d <- read.csv(file="./points.csv", header=TRUE, sep=",")
	x <- d$lng
	y <- d$lat
	w <- d$weight
	df <- data.frame(x,y)
	mean = geomean(df,w)
	.sdd <- function(t,mean) {
		x <- t$lng
		y <- t$lat
		x <- x-mean[1]
		y <- y-mean[2]
		x <- x*x
		y <- y*y
		result <- (Reduce("+",x)/length(x))+ (Reduce("+",y)/length(y))
		result <- sqrt(result)
		return(result)
	}
	.sdd(d,mean)

Edit: I was trying to run R script file in java. i figured it out. It was because the permission problem, I was not allowed to access the root of C drive.

Base on this [answer][3], I am not sure what should I modify in this line. I know that there are lots of Datums. if my list of lat/lng are mostly 22.0,144.0m is this line still suitable?

    CRS.new <- CRS("+proj=somerc +lat_0=46.9524056 +lon_0=7.43958333 +ellps=bessel +x_0=2600000 +y_0=1200000 +towgs84=674.374,15.056,405.346 +units=m +k_0=1 +no_defs")


  [1]: http://resources.esri.com/help/9.3/arcgisengine/java/gp_toolref/spatial_statistics_tools/standard_distance_spatial_statistics_.htm
  [2]: https://i.sstatic.net/je6em.gif
  [3]: https://gis.stackexchange.com/a/45266/86132