graduate.scala

import org.geoscript._
import layer.Shapefile, support.math.Interpolation, style.combinators._,
  style.io.SLD, io.Sink
import org.geotools.filter.text.ecql.ECQL.{ toFilter => cql }
import java.awt.Color

val states = Shapefile("geoscript/src/test/resources/data/states.shp")

val buckets =
  (states.features.map(_.get[Double]("PERSONS")).toSeq
    .sorted
    .grouped(math.rint(states.count / 10d).toInt)
    .map(x => (x.head, x.last))
    .toList)

val intervals = (0 until buckets.size) map (_ / (buckets.size - 1d))
val colorAt = Interpolation.Linear(new Color(0, 0, 0x66), Color.RED)
val widthAt = Interpolation.Linear(1d, 12d)

val style =
( for ((i, (min, max)) <- intervals zip buckets) yield
    Stroke(stroke=colorAt(i), width=widthAt(i)).where(
      cql("POPULATION BETWEEN %f AND %f".format(min, max)))
) reduce (_ and _)

SLD.write(style, Sink.stream(System.out))