/// <summary>
/// Returns a view that is a view of a single element
/// </summary>
/// <param name="element">The element to view</param>
/// <returns>The subview</returns>
public NdArray <T> Subview(long element)
{
if (element < 0)
{
element = this.Shape.Dimensions[0].Length + element;
}
if (element < 0 || element > this.Shape.Dimensions[0].Length)
{
throw new ArgumentOutOfRangeException("element");
}
//Special case
if (this.Shape.Dimensions.LongLength == 1)
{
long pos = this.Shape[element];
return(Reshape(new Shape(
new long[] { 1 }, //Single element
pos, //Offset to position
new long[] { this.Shape.Length - pos } //Skip the rest
)));
}
Shape.ShapeDimension[] dims = new Shape.ShapeDimension[this.Shape.Dimensions.Length - 1];
Array.Copy(this.Shape.Dimensions, 1, dims, 0, dims.Length);
//We need to modify the top dimension to skip the elements we wish to hide
long newoffset = this.Shape[element];
return(this.Reshape(new Shape(dims, newoffset)));
}
/// <summary>
/// Returns a view that is a view of a range of elements
/// </summary>
/// <param name="range">The range to view</param>
/// <param name="dim">The dimension to apply the range to</param>
/// <param name="removeIfSingleEl">True if the dimension is removed if it is a single element, false otherwise</param>
/// <returns>The subview</returns>
public NdArray <T> Subview(Range range, long dim, bool removeIfSingleEl = false)
{
long first = range.First < 0 ? (this.Shape.Dimensions[dim].Length) + range.First : range.First;
long offset = dim == this.Shape.Dimensions.LongLength ? this.Shape.Length : this.Shape.Offset + first * this.Shape.Dimensions[dim].Stride;
long last;
long stride;
if (range.Initialized)
{
if (range.NewDimension)
{
Shape.ShapeDimension[] n = new Shape.ShapeDimension[this.Shape.Dimensions.LongLength + 1];
Array.Copy(this.Shape.Dimensions, 0, n, 0, dim);
Array.Copy(this.Shape.Dimensions, dim, n, dim + 1, n.LongLength - (dim + 1));
n[dim] = new NumCIL.Shape.ShapeDimension(1, 0);
return(this.Reshape(new Shape(n, this.Shape.Offset)));
}
else if (range.SingleElement)
{
last = first;
}
else
{
last = range.Last <= 0 ? (this.Shape.Dimensions[dim].Length - 1) + range.Last : range.Last - 1;
}
stride = range.Stride;
}
else
{
last = this.Shape.Dimensions[dim].Length - 1;
stride = 1;
}
long j = 0;
Shape.ShapeDimension[] dimensions;
if (range.SingleElement && removeIfSingleEl)
{
dimensions = this.Shape.Dimensions.Where(x => j++ != dim).ToArray();
}
else
{
dimensions = this.Shape.Dimensions.Select(x =>
{
if (j++ == dim)
{
if (last * stride > this.Shape.Dimensions[dim].Length - 1)
{
last = (this.Shape.Dimensions[dim].Length - 1) / stride;
}
return(new Shape.ShapeDimension((last - first) + 1, stride * x.Stride));
}
else
{
return(x);
}
}).ToArray();
}
return(this.Reshape(new Shape(dimensions, offset)));
}