/// <summary>
/// Get a string out of a vector of chars.
/// </summary>
/// <param name="indices"></param>
/// <returns></returns>
/// <remarks>Performs a copy due to String .net-framework limitations.</remarks>
public string GetString(params int[] indices)
{
unsafe
{
if (Shape.dimensions.Length - 1 != indices.Length)
{
throw new ArgumentOutOfRangeException(nameof(indices), "GetString(int[]) can only accept coordinates that point to a vector of chars.");
}
Debug.Assert(typecode == NPTypeCode.Char);
UnmanagedStorage src = Storage.GetData(indices);
Debug.Assert(src.Shape.NDim == 1);
if (!Shape.IsContiguous || Shape.ModifiedStrides)
{
//this works faster than cloning.
var ret = new string('\0', src.Count);
fixed(char *retChars = ret)
{
var dst = new UnmanagedStorage(new ArraySlice <char>(new UnmanagedMemoryBlock <char>(retChars, ret.Length)), src.Shape.Clean());
MultiIterator.Assign(dst, src);
}
return(ret);
}
//new string always performs a copy, there is no need to keep reference to arr's unmanaged storage.
return(new string((char *)src.Address, 0, src.Count));
}
}
/// <summary>
/// Copies values from one array to another, broadcasting as necessary.
/// </summary>
/// <param name="dst">The array into which values are copied.</param>
/// <param name="src">The array from which values are copied.</param>
/// <remarks>https://docs.scipy.org/doc/numpy/reference/generated/numpy.copyto.html</remarks>
public static void copyto(NDArray dst, NDArray src) //todo! add where argument
{
if (dst == null)
{
throw new ArgumentNullException(nameof(dst));
}
if (src == null)
{
throw new ArgumentNullException(nameof(src));
}
//try to perform memory copy
if (dst.Shape.IsContiguous && src.Shape.IsContiguous && dst.dtype == src.dtype && src.size == dst.size)
{
unsafe
{
src.CopyTo(dst.Address);
return;
}
}
//perform manual copy with automatic casting
MultiIterator.Assign(dst.Storage, src.Storage);
}
/// <summary>
/// Join a sequence of arrays along an existing axis.
/// </summary>
/// <param name="axis">The axis along which the arrays will be joined. If axis is None, arrays are flattened before use. Default is 0.</param>
/// <param name="arrays">The arrays must have the same shape, except in the dimension corresponding to axis (the first, by default).</param>
/// <returns>The concatenated array.</returns>
/// <remarks>https://docs.scipy.org/doc/numpy/reference/generated/numpy.concatenate.html</remarks>
public static NDArray concatenate(NDArray[] arrays, int axis = 0)
{
//What we do is we have the axis which is the only dimension that is allowed to be different
//We need to perform a check if the dimensions actually match.
//After we have the axis ax=1 where shape is (3,ax,3) - ax is the only dimension that can vary.
//So if we got input of (3,5,3) and (3,1,3), we create a return shape of (3,6,3).
//We perform the assignment by iterating a slice: (:,n,:) on src and dst where dst while n of dst grows as we iterate all arrays.
if (arrays == null)
{
throw new ArgumentNullException(nameof(arrays));
}
if (arrays.Length == 0)
{
throw new ArgumentException("Value cannot be an empty collection.", nameof(arrays));
}
if (arrays.Length == 1)
{
return(arrays[0]);
}
var first = arrays[0];
var firstShape = (int[])first.shape.Clone();
while (axis < 0)
{
axis = first.ndim + axis; //translate negative axis
}
int i, j;
int axisSize = 0; //accumulated shape[axis] size for return shape.
NPTypeCode retType = first.GetTypeCode;
foreach (var src in arrays)
{
//accumulate the concatenated axis
var shape = src.shape;
axisSize += shape[axis];
if (ReferenceEquals(src, first))
{
continue;
}
var srcType = src.GetTypeCode;
//resolve what the return type should be and should we perform casting.
if (first.GetTypeCode != srcType)
{
if (srcType.CompareTo(retType) == 1)
{
retType = srcType;
}
}
if (shape.Length != first.ndim)
{
throw new IncorrectShapeException("all the input arrays must have same number of dimensions.");
}
//verify the shapes are equal
for (j = 0; j < shape.Length; j++)
{
if (axis == j)
{
continue;
}
if (shape[j] != firstShape[j])
{
throw new IncorrectShapeException("all the input array dimensions except for the concatenation axis must match exactly.");
}
}
}
//prepare return shape
firstShape[axis] = axisSize;
var retShape = new Shape(firstShape);
var dst = new NDArray(retType, retShape);
var accessorDst = new Slice[retShape.NDim];
var accessorSrc = new Slice[retShape.NDim];
for (i = 0; i < accessorDst.Length; i++)
{
accessorSrc[i] = accessorDst[i] = Slice.All;
}
accessorSrc[axis] = Slice.Index(0);
accessorDst[axis] = Slice.Index(0);
foreach (var src in arrays)
{
var len = src.shape[axis];
for (i = 0; i < len; i++)
{
var writeTo = dst[accessorDst];
var writeFrom = src[accessorSrc];
MultiIterator.Assign(writeTo.Storage, writeFrom.Storage);
accessorSrc[axis]++;
accessorDst[axis]++; //increment every step
}
accessorSrc[axis] = Slice.Index(0); //reset src
}
return(dst);
}
/// <summary>
/// Converts <see cref="NDArray"/> to a <see cref="Bitmap"/>.
/// </summary>
/// <param name="nd">The <see cref="NDArray"/> to copy pixels from, <see cref="Shape"/> is ignored completely. If nd.Unsafe.Shape.IsContiguous == false then a copy is made.</param>
/// <param name="width">The height of the <see cref="Bitmap"/></param>
/// <param name="height">The width of the <see cref="Bitmap"/></param>
/// <param name="format">The format of the expected bitmap, Must be matching to given NDArray otherwise unexpected results might occur.</param>
/// <returns>A <see cref="Bitmap"/></returns>
/// <exception cref="ArgumentException">When nd.size != width*height, which means the ndarray be turned into the given bitmap size.</exception>
public static unsafe Bitmap ToBitmap(this NDArray nd, int width, int height, PixelFormat format = PixelFormat.DontCare)
{
if (nd == null)
{
throw new ArgumentNullException(nameof(nd));
}
//if flat then initialize based on given format
if (nd.ndim == 1 && format != PixelFormat.DontCare)
{
nd = nd.reshape(1, height, width, format.ToBytesPerPixel()); //theres a check internally for size mismatch.
}
if (nd.ndim != 4)
{
throw new ArgumentException("ndarray was expected to be of 4-dimensions, (1, bmpData.Height, bmpData.Width, bytesPerPixel)");
}
if (nd.shape[0] != 1)
{
throw new ArgumentException($"ndarray has more than one picture in it ({nd.shape[0]}) based on the first dimension.");
}
var bbp = nd.shape[3]; //bytes per pixel.
if (bbp != extractFormatNumber())
{
throw new ArgumentException($"Given PixelFormat: {format} does not match the number of bytes per pixel in the 4th dimension of given ndarray.");
}
if (bbp * width * height != nd.size)
{
throw new ArgumentException($"The expected size does not match the size of given ndarray. (expected: {bbp * width * height}, actual: {nd.size})");
}
var ret = new Bitmap(width, height, format);
var bitdata = ret.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, format);
try
{
var dst = new ArraySlice <byte>(new UnmanagedMemoryBlock <byte>((byte *)bitdata.Scan0, bitdata.Stride * bitdata.Height));
if (nd.Shape.IsContiguous)
{
nd.CopyTo(dst);
}
else
{
MultiIterator.Assign(new UnmanagedStorage(dst, Shape.Vector(bitdata.Stride * bitdata.Height)), nd.Unsafe.Storage);
}
}
finally
{
ret.UnlockBits(bitdata);
}
return(ret);
int extractFormatNumber()
{
if (format == PixelFormat.DontCare)
{
switch (bbp)
{
case 3:
format = PixelFormat.Format24bppRgb;
break;
case 4:
format = PixelFormat.Format32bppArgb;
break;
case 6:
format = PixelFormat.Format48bppRgb;
break;
case 8:
format = PixelFormat.Format64bppArgb;
break;
}
return(bbp);
}
return(format.ToBytesPerPixel());
}
}
