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DoubleNdArray

public interface DoubleNdArray
Known Indirect Subclasses

An NdArray of doubles.

Public Methods

abstract DoubleNdArray
copyTo ( NdArray <Double> dst)
abstract NdArraySequence < DoubleNdArray >
elements (int dimensionIdx)
Returns a sequence of all elements at a given dimension.
abstract DoubleNdArray
get (long... coordinates)
Returns the N-dimensional element of this array at the given coordinates.
abstract double
getDouble (long... coordinates)
Returns the double value of the scalar found at the given coordinates.
abstract Double
getObject (long... coordinates)
Returns the value of the scalar found at the given coordinates.
abstract DoubleNdArray
read ( DataBuffer <Double> dst)
abstract DoubleNdArray
abstract NdArraySequence < DoubleNdArray >
scalars ()
Returns a sequence of all scalars in this array.
abstract DoubleNdArray
set ( NdArray <Double> src, long... coordinates)
abstract DoubleNdArray
setDouble (double value, long... coordinates)
Assigns the double value of the scalar found at the given coordinates.
abstract DoubleNdArray
setObject (Double value, long... coordinates)
abstract DoubleNdArray
slice ( Index... indices)
Creates a multi-dimensional view (or slice) of this array by mapping one or more dimensions to the given index selectors.
abstract DoubleNdArray
write ( DataBuffer <Double> src)
abstract DoubleNdArray

Inherited Methods

Public Methods

public abstract DoubleNdArray copyTo ( NdArray <Double> dst)

public abstract NdArraySequence < DoubleNdArray > elements (int dimensionIdx)

Returns a sequence of all elements at a given dimension.

Logically, 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 size() values.

For example, given a n x m matrix on the [x, y] axes, elements are iterated in the following order:

x 0 y 0 , x 0 y 1 , ..., x 0 y m-1 , x 1 y 0 , x 1 y 1 , ..., x n-1 y m-1

The returned sequence can then be iterated to visit each elements, either by calling forEach(Consumer) or 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);
    });
 }

Parameters
dimensionIdx index of the dimension
Returns
  • an NdArray sequence

public abstract DoubleNdArray get (long... coordinates)

Returns the N-dimensional element of this array at the given coordinates.

Elements 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))

Parameters
coordinates coordinates of the element to access, none will return this array
Returns
  • the element at this index

public abstract double getDouble (long... coordinates)

Returns the double value of the scalar found at the given coordinates.

To 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:

DoubleNdArray matrix = NdArrays.ofDoubles(shape(2, 2));  // matrix rank = 2
  matrix.getDouble(0, 1);  // succeeds, returns 0.0
  matrix.getDouble(0);  // throws IllegalRankException

  DoubleNdArray scalar = matrix.get(0, 1);  // scalar rank = 0
  scalar.getDouble();  // succeeds, returns 0.0
 

Parameters
coordinates coordinates of the scalar to resolve
Returns
  • value of that scalar
Throws
IndexOutOfBoundsException if some coordinates are outside the limits of their respective dimension
IllegalRankException if number of coordinates is not sufficient to access a scalar element

public abstract Double getObject (long... coordinates)

Returns the value of the scalar found at the given coordinates.

To 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
 
Note: if this array stores values of a primitive type, prefer the usage of the specialized method in the subclass for that type. For example, floatArray.getFloat(0); .

Parameters
coordinates coordinates of the scalar to resolve
Returns
  • value of that scalar

public abstract DoubleNdArray read ( DataBuffer <Double> dst)

public abstract DoubleNdArray read ( DoubleDataBuffer dst)

public abstract NdArraySequence < DoubleNdArray > scalars ()

Returns a sequence of all scalars in this array.

This is equivalent to call elements(shape().numDimensions() - 1)

Returns
  • an NdArray sequence

public abstract DoubleNdArray set ( NdArray <Double> src, long... coordinates)

public abstract DoubleNdArray setDouble (double value, long... coordinates)

Assigns the double value of the scalar found at the given coordinates.

To 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:

DoubleNdArray matrix = NdArrays.ofDoubles(shape(2, 2));  // matrix rank = 2
  matrix.setDouble(10.0, 0, 1);  // succeeds
  matrix.setDouble(10.0, 0);  // throws IllegalRankException

  DoubleNdArray scalar = matrix.get(0, 1);  // scalar rank = 0
  scalar.setDouble(10.0);  // succeeds
 

Parameters
value value to assign
coordinates coordinates of the scalar to assign
Returns
  • this array
Throws
IndexOutOfBoundsException if some coordinates are outside the limits of their respective dimension
IllegalRankException if number of coordinates is not sufficient to access a scalar element

public abstract DoubleNdArray setObject (Double value, long... coordinates)

public abstract DoubleNdArray slice ( Index... indices)

Creates a multi-dimensional view (or slice) of this array by mapping one or more dimensions to the given index selectors.

Slices 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
    });
 }

Parameters
indices index selectors per dimensions, starting from dimension 0 of this array.
Returns
  • the element resulting of the index selection

public abstract DoubleNdArray write ( DataBuffer <Double> src)

public abstract DoubleNdArray write ( DoubleDataBuffer src)