/// <summary>
/// Calculates the difference between adjoining elements along the specified axes.
/// </summary>
/// <param name="axis">The axis to operate along.</param>
/// <param name="source">The NdArray containing the source values.</param>
/// <returns>The differences NdArray. It has one element less in dimension <paramref name="axis"/> as the source NdArray.</returns>
public static NdArray <T> DiffAxis(int axis, NdArray <T> source)
{
NdArray <T> .CheckAxis(axis, source);
var shiftRanges = new List <IRange>();
var cutRanges = new List <IRange>();
for (var index = 0; index < source.NumDimensions; index++)
{
if (index == axis)
{
shiftRanges.Add(RangeFactory.Range(1, SpecialIdx.None));
cutRanges.Add(RangeFactory.Range(SpecialIdx.None, source.Shape[index] - 2));
}
else
{
shiftRanges.Add(RangeFactory.All);
cutRanges.Add(RangeFactory.All);
}
}
var shiftArray = source[shiftRanges.ToArray()];
var cutArray = source[cutRanges.ToArray()];
return(shiftArray - cutArray);
}
/// <summary>
/// Concatenates NdArrays along an axis.
/// </summary>
/// <param name="axis">The concatenation axis.</param>
/// <param name="sources">Sequence of NdArrays to concatenate.</param>
/// <returns>The concatenated NdArray.</returns>
public static NdArray <T> Concat(int axis, NdArray <T>[] sources)
{
if (sources.Length == 0)
{
throw new ArgumentException("Cannot concatenate empty sequence of NdArray.", "sources");
}
var shape = sources[0].Shape.Select(s => s).ToArray();
if (!(axis >= 0 && axis < shape.Length))
{
var errorMessage = string.Format("Concatenation axis {0} is out of range for shape {1}.", axis, ErrorMessage.ShapeToString(shape));
throw new ArgumentOutOfRangeException("axis", errorMessage);
}
var arrayIndex = 0;
foreach (var source in sources)
{
if (!Enumerable.SequenceEqual(List.Without(axis, source.Shape), List.Without(axis, shape)))
{
var errorMessage = string.Format("Concatentation element with index {0} with shape{1} must be equal to shape {2} of the first element, except in the concatenation axis {3}", arrayIndex, ErrorMessage.ShapeToString(source.Shape), ErrorMessage.ShapeToString(shape), axis);
throw new ArgumentException(errorMessage, "sources");
}
arrayIndex++;
}
var totalSize = sources.Sum(i => i.Shape[axis]);
var concatShape = List.Set(axis, totalSize, shape);
var result = new NdArray <T>(concatShape, sources[0].Storage.Device);
var position = 0;
foreach (var source in sources)
{
var arrayLength = source.Shape[axis];
if (arrayLength > 0)
{
var range = Enumerable.Range(0, shape.Length).Select(idx =>
{
if (idx == axis)
{
return(RangeFactory.Range(position, position + arrayLength - 1));
}
return(RangeFactory.All);
});
result[range.ToArray()] = source;
position += arrayLength;
}
}
return(result);
}
public void Range_ReturnRange()
{
// arrange & action
var rng = RangeFactory.Range(10, 30, 2) as Range;
// assert
Assert.IsInstanceOfType(rng, typeof(Range));
Assert.AreEqual(10, rng.Start);
Assert.AreEqual(30, rng.Stop);
Assert.AreEqual(2, rng.Step);
}
public void RangeArgsToString_TwoRangesWithStep()
{
// arrange
var objects = new[] { RangeFactory.Range(0, 4, 2), RangeFactory.Range(0, 3) };
// action
var message = ErrorMessage.RangeArgsToString(objects);
// assert
Assert.AreEqual("[0:4:2, 0:3]", message);
}
public void RangeArgsToString_RangeDefault()
{
// arrange
var objects = new[] { RangeFactory.Range(0, 2) };
// action
var message = ErrorMessage.RangeArgsToString(objects);
// assert
Assert.AreEqual("[0:2]", message);
}
