public abstract class AbstractDenseNdArray<T,U extends NdArray<T>> extends AbstractNdArray<T,U>
dimensions| Modifier | Constructor and Description |
|---|---|
protected |
AbstractDenseNdArray(DimensionalSpace dimensions) |
| Modifier and Type | Method and Description |
|---|---|
protected abstract DataBuffer<T> |
buffer() |
NdArraySequence<U> |
elements(int dimensionIdx)
Returns a sequence of all elements at a given dimension.
|
boolean |
equals(Object obj)
Checks equality between n-dimensional arrays.
|
U |
get(long... coords)
Returns the N-dimensional element of this array at the given coordinates.
|
T |
getObject(long... coords)
Returns the value of the scalar found at the given coordinates.
|
int |
hashCode() |
U |
read(DataBuffer<T> dst)
Read the content of this N-dimensional array into the destination buffer.
|
U |
set(NdArray<T> src,
long... coordinates)
Assigns the value of the N-dimensional element found at the given coordinates.
|
U |
setObject(T value,
long... coords)
Assigns the value of the scalar found at the given coordinates.
|
U |
slice(Index... indices)
Creates a multi-dimensional view (or slice) of this array by mapping one or more dimensions
to the given index selectors.
|
U |
slice(long position,
DimensionalSpace sliceDimensions) |
protected void |
slowCopyTo(NdArray<T> array) |
U |
write(DataBuffer<T> src)
Write the content of this N-dimensional array from the source buffer.
|
dimensions, scalars, shape, slowEquals, slowHashCodeprotected AbstractDenseNdArray(DimensionalSpace dimensions)
public NdArraySequence<U> elements(int dimensionIdx)
NdArrayLogically, the N-dimensional array can be flatten in a single vector, where the scalars of
the (n - 1)th element precedes those of the (n)th element, for a total of
NdArray.size() values.
For example, given a n x m matrix on the [x, y] axes, elements are iterated in
the following order:
x0y0, x0y1, ..., x0ym-1, x1y0, x1y1, ..., xn-1ym-1
The returned sequence can then be iterated to visit each elements, either by calling
Iterable.forEach(Consumer) or NdArraySequence.forEachIndexed(BiConsumer).
// Iterate matrix for initializing each of its vectors
matrixOfFloats.elements(0).forEach(v -> {
v.set(vector(1.0f, 2.0f, 3.0f));
});
// Iterate a vector for reading each of its scalar
vectorOfFloats.scalars().forEachIdx((coords, s) -> {
System.out.println("Value " + s.getFloat() + " found at " + coords);
});
dimensionIdx - index of the dimensionNdArray sequencepublic U slice(long position, DimensionalSpace sliceDimensions)
public U slice(Index... indices)
NdArraySlices allow to traverse an N-dimensional array in any of its axis and/or to filter only
elements of interest. For example, for a given matrix on the [x, y] axes, it is
possible to iterate elements at y=0 for all x.
Any changes applied to the returned slice affect the data of this array as well, as there is no copy involved.
Example of usage:
FloatNdArray matrix3d = NdArrays.ofFloats(shape(3, 2, 4)); // with [x, y, z] axes
// Iterates elements on the x axis by preserving only the 3rd value on the z axis,
// (i.e. [x, y, 2])
matrix3d.slice(all(), all(), at(2)).elements(0).forEach(m -> {
assertEquals(shape(2), m); // y=2, z=0 (scalar)
});
// Creates a slice that contains only the last element of the y axis and elements with an
// odd `z` coordinate.
FloatNdArray slice = matrix3d.slice(all(), at(1), odd());
assertEquals(shape(3, 2), slice.shape()); // x=3, y=0 (scalar), z=2 (odd coordinates)
// Iterates backward the elements on the x axis
matrix3d.slice(flip()).elements(0).forEach(m -> {
assertEquals(shape(2, 4), m); // y=2, z=4
});
indices - index selectors per dimensions, starting from dimension 0 of this array.public U get(long... coords)
NdArrayElements of any of the dimensions of this array can be retrieved. For example, if the number of coordinates is equal to the number of dimensions of this array, then a rank-0 (scalar) array is returned, which value can then be obtained by calling `array.getObject()`.
Any changes applied to the returned elements affect the data of this array as well, as there is no copy involved.
Note that invoking this method is an equivalent and more efficient way to slice this array
on single scalar, i.e. array.get(x, y, z) is equal to
array.slice(at(x), at(y), at(z))
coords - coordinates of the element to access, none will return this arraypublic T getObject(long... coords)
NdArrayTo access the scalar element, the number of coordinates provided must be equal to the number of dimensions of this array (i.e. its rank). For example:
FloatNdArray matrix = NdArrays.ofFloats(shape(2, 2)); // matrix rank = 2
matrix.getObject(0, 1); // succeeds, returns 0.0f
matrix.getObject(0); // throws IllegalRankException
FloatNdArray scalar = matrix.get(0, 1); // scalar rank = 0
scalar.getObject(); // succeeds, returns 0.0f
floatArray.getFloat(0); .coords - coordinates of the scalar to resolvepublic U set(NdArray<T> src, long... coordinates)
NdArrayThe number of coordinates provided can be anywhere between 0 and rank - 1. For example:
FloatNdArray matrix = NdArrays.ofFloats(shape(2, 2)); // matrix rank = 2
matrix.set(vector(10.0f, 20.0f), 0); // success
matrix.set(scalar(10.0f), 1, 0); // success
src - an array of the values to assigncoordinates - coordinates of the element to assignpublic U setObject(T value, long... coords)
NdArrayTo access the scalar element, the number of coordinates provided must be equal to the number of dimensions of this array (i.e. its rank). For example:
FloatNdArray matrix = NdArrays.ofFloats(shape(2, 2)); // matrix rank = 2
matrix.setObject(10.0f, 0, 1); // succeeds
matrix.setObject(10.0f, 0); // throws IllegalRankException
FloatNdArray scalar = matrix.get(0, 1); // scalar rank = 0
scalar.setObject(10.0f); // succeeds
floatArray.setFloat(10.0f, 0); value - the value to assigncoords - coordinates of the scalar to assignpublic U read(DataBuffer<T> dst)
NdArrayThe size of the buffer must be equal or greater to the NdArray.size() of this
array, or an exception is thrown. After the copy, content of the buffer and of the array can be
altered independently, without affecting each other.
dst - the destination bufferDataBuffer.size()public U write(DataBuffer<T> src)
NdArrayThe size of the buffer must be equal or greater to the NdArray.size() of this
array, or an exception is thrown. After the copy, content of the buffer and of the array can be
altered independently, without affecting each other.
src - the source bufferDataBuffer.size()public boolean equals(Object obj)
NdArrayAn array is equal to another object if this object is another NdArray of the
same shape, type and the elements are equal and in the same order. For example:
IntNdArray array = NdArrays.ofInts(Shape.of(2, 2))
.set(NdArrays.vectorOf(1, 2), 0)
.set(NdArrays.vectorOf(3, 4), 1);
assertEquals(array, StdArrays.ndCopyOf(new int[][] {{1, 2}, {3, 4}})); // true
assertEquals(array, StdArrays.ndCopyOf(new Integer[][] {{1, 2}, {3, 4}})); // true, as Integers are equal to ints
assertNotEquals(array, NdArrays.vectorOf(1, 2, 3, 4)); // false, different shapes
assertNotEquals(array, StdArrays.ndCopyOf(new int[][] {{3, 4}, {1, 2}})); // false, different order
assertNotEquals(array, StdArrays.ndCopyOf(new long[][] {{1L, 2L}, {3L, 4L}})); // false, different types
Note that the computation required to verify equality between two arrays can be expensive in some cases and therefore, it is recommended to not use this method in a critical path where performances matter.
protected abstract DataBuffer<T> buffer()
protected void slowCopyTo(NdArray<T> array)
slowCopyTo in class AbstractNdArray<T,U extends NdArray<T>>Copyright © 2015–2020. All rights reserved.