/// <summary>
/// Generates npy header by this instance.
/// </summary>
/// <returns></returns>
public byte[] GenerateHeader()
{
var headerText =
"{"
+ $"'descr': '{NumpyType.Expression}', "
+ $"'fortran_order': {(FortranOrder ? "True" : "False")}, "
+ $"'shape': ({string.Join(", ", Shape)}{(Shape.Length <= 1 ? "," : "")}), "
+ "}";
var header = Encoding.UTF8.GetBytes(headerText);
var bufferLen =
NdMath.Max(128, Align16(_HeaderMagicNumber.Length + 4 + header.Length + 1));
var version = bufferLen < 65536 ? (byte)1 : (byte)2;
var headerDicAlign = _HeaderDicAligns[version];
var buffer = new byte[bufferLen];
buffer.AsSpan().Fill(0x20);
Buffer.BlockCopy(_HeaderMagicNumber, 0, buffer, 0, _HeaderMagicNumber.Length);
buffer[_MajorVersionAlign] = version;
buffer[_MinorVersionAlign] = 0;
switch (version)
{
case 1:
LittleEndiannessBitConverter.Instance.TryWritePrimitive(buffer.AsSpan(_HeaderLenAlign),
(ushort)(bufferLen - headerDicAlign));
break;
case 2:
LittleEndiannessBitConverter.Instance.TryWritePrimitive(buffer.AsSpan(_HeaderLenAlign),
(ushort)(bufferLen - headerDicAlign));
break;
}
Buffer.BlockCopy(header, 0, buffer, headerDicAlign, header.Length);
buffer[bufferLen - 1] = 0x0A;
return(buffer);
}
/// <summary>
/// Creates new <see cref="T:NeodymiumDotNet.Random.MersenneTwisterGenerator" /> instance with seed array.
/// </summary>
/// <param name="seedArray"></param>
public MersenneTwisterGenerator(IReadOnlyList <int> seedArray)
: this(19650218)
{
var i = 1;
var j = 0;
var k = NdMath.Max(_N, seedArray.Count);
for (; k > 0; --k)
{
var prev = _mt[i - 1];
_mt[i] = (_mt[i] ^ ((prev ^ (prev >> 30)) * 1664525u)) + (uint)seedArray[j] + (uint)j;
++i;
++j;
if (i >= _N)
{
_mt[0] = _mt[_N - 1];
i = 1;
}
if (j >= seedArray.Count)
{
j = 0;
}
}
for (k = _N - 1; k > 0; --k)
{
var prev = _mt[i - 1];
_mt[i] = (_mt[i] ^ ((prev ^ (prev >> 30)) * 1566083941)) - (uint)i;
++i;
if (i >= _N)
{
_mt[0] = _mt[_N - 1];
i = 1;
}
}
_mt[0] = _UpperMask;
}