// import GeoScript modules
import geoscript.layer.*
import geoscript.feature.*
import geoscript.geom.*

// This is the Shapefile we want to extract centroids from
Shapefile shp = new Shapefile('states.shp')

// Create a new Schema (based on the above Shapefile, but with Point Geometry)
Schema schema = shp.schema.changeGeometryType('Point','states_centroids')

// Create the new centroid Layer
Layer centroidLayer = shp.workspace.create(schema)

// Use the Cursor to loop through each Feature in the Shapefile
Cursor cursor = shp.cursor
while(cursor.hasNext()) {

   // Get the next Feature
   Feature f = cursor.next()
 
   // Create a Map for the new attributes
   Map attributes = [:]

   // For each attribute in the shapefile
   f.attributes.each{k,v ->

      // If its Geometry, find the centroid
      if (v instanceof Geometry) {
          attributes[k] = v.centroid
      }
      // Else, they stay the same
      else {
         attributes[k] = v
      }
   }

   // Create a new Feature with the new attributes
   Feature feature = schema.feature(attributes, f.id)

   // Add it to the centroid Layer
   centroidLayer.add(feature)
}

// Always remember to close the cursor
cursor.close()