/// <summary>
/// For axes-formed linq, operator, calculates the partial array shape.
/// </summary>
/// <param name="sourceShape"></param>
/// <param name="axes"></param>
/// <param name="flattenIndex"></param>
/// <returns></returns>
internal static IndexOrRange[] CalculatePartialShape(
IndexArray sourceShape,
ReadOnlySpan <int> axes,
int flattenIndex)
{
var len = sourceShape.Length;
var newShape = CalculateAxesFormedShape(sourceShape, axes);
var indicesOnThis = NdArrayImpl.ToShapedIndices(newShape, flattenIndex);
var indexOrRangesOnSource = new IndexOrRange[len];
for (int i = 0, j = 0; i < len; ++i)
{
if (!axes.Contains(i))
{
indexOrRangesOnSource[i] = new Index(indicesOnThis[j], false);
++j;
}
else
{
indexOrRangesOnSource[i] = Range.Whole;
}
}
return(indexOrRangesOnSource);
}
/// <summary>
/// [Pure] Gets enumerable object of this.
/// </summary>
/// <returns></returns>
public IEnumerable <NdArray <T> > AsEnumerable(int axis)
{
var index = Enumerable
.Range(0, Rank)
.Select(_ => (IndexOrRange)Range.Whole)
.ToArray();
for (var i = 0; i < Shape[axis]; ++i)
{
index[axis] = new IndexOrRange(i);
yield return(this[index]);
}
}