geotrellis.raster.mapalgebra.focal.Min.scala Maven / Gradle / Ivy

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GeoTrellis is an open source geographic data processing engine for high performance applications.

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package geotrellis.raster.mapalgebra.focal

import geotrellis.raster._

/**
 * Computes the minimum value of a neighborhood for a given raster
 *
 * @note            Min does not currently support Double raster data.
 *                  If you use a Tile with a Double CellType (FloatConstantNoDataCellType, DoubleConstantNoDataCellType)
 *                  the data values will be rounded to integers.
 */
object Min {
  def calculation(tile: Tile, n: Neighborhood, bounds: Option[GridBounds] = None): FocalCalculation[Tile] = {

    if (tile.cellType.isFloatingPoint)
      new CursorCalculation[Tile](tile, n, bounds)
        with ArrayTileResult
      {
        def calc(r: Tile, cursor: Cursor) = {
          var m: Double = Double.NaN
          cursor.allCells.foreach { (col, row) =>
            val v = r.getDouble(col, row)
            if (isData(v) && (v < m || isNoData(m))) {
              m = v
            }
          }
          resultTile.setDouble(cursor.col, cursor.row, m)
        }
      }

    else
      new CursorCalculation[Tile](tile, n, bounds)
        with ArrayTileResult
      {
        def calc(r: Tile, cursor: Cursor) = {
          var m = NODATA
          cursor.allCells.foreach { (col, row) =>
            val v = r.get(col, row)
            if(isData(v) && (v < m || isNoData(m))) { m = v }
          }

          resultTile.set(cursor.col, cursor.row, m)
        }
      }
  }

  def apply(tile: Tile, n: Neighborhood, bounds: Option[GridBounds] = None): Tile =
    calculation(tile, n, bounds).execute()
}