private static NdArray <T> Dot2x2 <T>(IBufferNdArrayImpl <T> x, IBufferNdArrayImpl <T> yT)
{
// x .Shape = [m, p]
// yT.Shape = [n, p]
// retval.Shape = [m, n]
var p = x.Shape[1];
Guard.AssertShapeMatch(
p == yT.Shape[1],
$"x.Shape[1] = {p}, y.Shape[0] = {yT.Shape[1]}");
var m = x.Shape[0];
var n = yT.Shape[0];
var resImpl = new RawNdArrayImpl <T>(new IndexArray(m, n));
var xBuff = x.Buffer;
var yTBuff = yT.Buffer;
var resBuff = resImpl.Buffer.Span;
for (var i = 0; i < m; ++i)
{
for (var j = 0; j < n; ++j)
{
resBuff[n * i + j] = VectorOperation.Dot(xBuff.Slice(i * p, p), yTBuff.Slice(j * p, p));
}
}
return(new NdArray <T>(resImpl));
}
public static bool TryGetBufferImpl <T>(this INdArray <T> array, [NotNullWhen(true)] out IBufferNdArrayImpl <T>?result)
{
if ((array as INdArrayInternal <T>)?.Entity is IBufferNdArrayImpl <T> xresult)
{
result = xresult;
return(true);
}
result = default;
return(false);
}
/// <summary>
/// [Pure] Projects each element of a NdArray into a new form.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="ndarray"> A NdArray for values to invoke a transform function on. </param>
/// <param name="selector"> A transform function to apply to each element. </param>
/// <returns> [<c>$ReturnValue.Shape == NdArray.Shape</c>] </returns>
public static NdArray <T> Select <T>(
this NdArray <T> ndarray,
Expression <Func <T, T> > selector)
where T : unmanaged
{
Guard.AssertArgumentNotNull(ndarray, nameof(ndarray));
Guard.AssertArgumentNotNull(selector, nameof(selector));
ReadOnlyMemory <T> source = ndarray.Entity switch
{
IBufferNdArrayImpl <T> romProvider => romProvider.Buffer,
_ => default(ReadOnlyMemory <T>?),
} ?? throw new NotSupportedException();
/// <summary>
/// [Pure] Applies selector against each corresponding element set of input NdArrays.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="ndarray1"></param>
/// <param name="ndarray2"> [<c>ndarray1.Shape == ndarray2.Shape</c>] </param>
/// <param name="selector"></param>
/// <returns></returns>
public static NdArray <T> Zip <T>(this
NdArray <T> ndarray1,
NdArray <T> ndarray2,
Expression <Func <T, T, T> > selector
)
where T : unmanaged
{
ReadOnlyMemory <T> getSource(NdArray <T> ndarray)
=> ndarray.Entity switch
{
IBufferNdArrayImpl <T> romProvider => romProvider.Buffer,
_ => default(ReadOnlyMemory <T>?),
}
private static NdArray <T> Dot1x1 <T>(IBufferNdArrayImpl <T> x, IBufferNdArrayImpl <T> y)
{
// x.Shape = [p]
// y.Shape = [p]
// retval.Shape = [1]
var p = x.Shape[0];
Guard.AssertShapeMatch(p == y.Shape[0], $"x.Shape[0] = {p}, y.Shape[0] = {y.Shape[0]}");
var resImpl = new RawNdArrayImpl <T>(new IndexArray(1));
var xBuff = x.Buffer;
var yBuff = y.Buffer;
var resBuff = resImpl.Buffer.Span;
resBuff[0] = VectorOperation.Dot(xBuff, yBuff);
return(new NdArray <T>(resImpl));
}
private static NdArray <T> Dot2x1 <T>(IBufferNdArrayImpl <T> x, IBufferNdArrayImpl <T> y)
{
// x.Shape = [m, p]
// y.Shape = [p]
// retval.Shape = [m]
var p = x.Shape[1];
Guard.AssertShapeMatch(p == y.Shape[0], $"x.Shape[1] = {p}, y.Shape[0] = {y.Shape[0]}");
var m = x.Shape[0];
var resImpl = new RawNdArrayImpl <T>(new IndexArray(m));
var xBuff = x.Buffer;
var yBuff = y.Buffer;
var resBuff = resImpl.Buffer.Span;
for (var i = 0; i < m; ++i)
{
resBuff[i] = VectorOperation.Dot(xBuff.Slice(i * p, p), yBuff);
}
return(new NdArray <T>(resImpl));
}