geotrellis.raster.mapalgebra.zonal.IntZonalHistogram.scala Maven / Gradle / Ivy

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/*
 * Copyright (c) 2014 Azavea.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package geotrellis.raster.mapalgebra.zonal

import geotrellis.raster._
import geotrellis.raster.histogram._

import spire.syntax.cfor._

import scala.collection.mutable


object IntZonalHistogram extends ZonalHistogram[Int] {

  def apply(tile: Tile, zones: Tile): Map[Int, Histogram[Int]] = {
    val histMap = mutable.Map[Int, MutableHistogram[Int]]()

    val rows  = tile.rows
    val cols  = tile.cols

    cfor(0)(_ < rows, _ + 1) { row =>
      cfor(0)(_ < cols, _ + 1) { col =>
        val v = tile.get(col, row)
        val z = zones.get(col, row)
        if(!histMap.contains(z)) { histMap(z) = FastMapHistogram() }
        histMap(z).countItem(v)
      }
    }

    histMap.toMap
  }
}