Sources

        val valid = geotrellis.data.geojson.GeoJsonReader.parse(geoJson).get.filter(node => node.geom.isValid && node.geom.getGeometryType == "Polygon").map {
          g => (Polygon(g.geom,0), g.geom.getCentroid.getCoordinate)
        }
        val results = months.flatMap {
          month => {
            val raster = RasterSource(store, s"${month}${year}NDVI_TOA_UTM14")
            val mask = RasterSource(store, s"${month}${year}ACCA_State_UTM14")
            val masked = raster.localMask(mask, 1, NODATA).cached
            val sources = valid.map {
              case (poly, coord) =>
                masked.zonalMean(poly).map {
                  result => if (isNoData(result)) (coord, month, "")
                  else
                    (coord, month, math.round(result).toString)
                }
            }

            val ds = DataSource.fromSources(sources)
            ds.run match {
              case Complete (result,_) => result
            }
          }
        }

val valid = geotrellis.data.geojson.GeoJsonReader.parse(geoJson).get.filter(node => node.geom.isValid && node.geom.getGeometryType == "Polygon").map {
  g => (Polygon(g.geom,0), g.geom.getCentroid.getCoordinate)
}

val months: Seq[String] = ???

val monthSources: Seq[SeqSource[(Coordinate, String, String)]] = 
  months.map { month =>
    val raster = RasterSource(store, s"${month}${year}NDVI_TOA_UTM14")
    val mask = RasterSource(store, s"${month}${year}ACCA_State_UTM14")
    val masked = raster.localMask(mask, 1, NODATA).cached
    val sources = valid.map {
      case (poly, coord) =>
        masked.zonalMean(poly).map {
          result => if (isNoData(result)) (coord, month, "")
          else
            (coord, month, math.round(result).toString)
        }
    }

    val ds = DataSource.fromSources(sources)
    ds.run match {
      case Complete (result,_) => result
    }
  }

val ds: SeqSource[Seq[(Coordinate, String, String)]] = 
  DataSource.fromSources(monthSources)

ds.run match {
  case Complete(results: Seq[Seq[(Coordinate, String, String)]], _) =>
    results.flatten
  case _ => sys.error("boom")
}