Potential Error With Histogram[Double]

[jbouffard]

It appears there's an issue when calling binCounts on a Histogram[Double].

scala> val tile = DoubleArrayTile(Array[Double](1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 2, 3, 0, 0), 4, 4)
tile: geotrellis.raster.DoubleArrayTile = DoubleConstantNoDataArrayTile([D@4a211bbe,4,4)

scala> tile.histogramDouble.binCounts
res19: Seq[(Double, Long)] = ArraySeq((0.0,0), (1.0,6), (2.0,4), (3.0,2))

As can be seen from the example, the total counts for each value is off. For instance, 0 returned a count of 0, but it really occurs 9 times. It could be that these values are correct since Histogram[Double] works from approximations. However, it would be worth investigating to make sure.

It should be noted, that this problem is not witnessed in Histogram[Int]:

scala> val tile2 = IntArrayTile(Array[Int](1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 2, 3, 0, 0), 4, 4)
tile2: geotrellis.raster.IntArrayTile = IntConstantNoDataArrayTile([I@666100d,4,4)

scala> tile2.histogram.binCounts
res20: Seq[(Int, Long)] = ArraySeq((0,8), (1,6), (2,1), (3,1))

[Frophie]

histogramDouble(numBuckets) and .median() result and so on also quite wrong, hope authors can fix this...

[Frophie]

Here is another test case:

    val tile = DoubleArrayTile(Array[Double](
      52, 54, 61,
      32, 52, 50,
      11, 21, 18), 3, 3)

    val result = tile.histogramDouble(3)
    result.binCounts.foreach(println(_))
    println(result.median().get)

present result:

(16.666666666666668,0)
(32.0,0)
(53.8,0)
34.18

[jamesmcclain]

I will take a look.