NdArray

Copy the content of this array to the destination array.

The shape() of the destination array must be equal to the shape of this array, or an exception is thrown. After the copy, the content of both arrays can be altered independently, without affecting each other.

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:

x₀y₀, x₀y₁, ..., x₀y_m-1, x₁y₀, x₁y₁, ..., x_n-1y_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);
    });
 }

Checks equality between n-dimensional arrays.

An 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.

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))

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
 

Read the content of this N-dimensional array into the destination buffer.

The size of the buffer must be equal or greater to the 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.

Returns a sequence of all scalars in this array.

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

Assigns the value of the N-dimensional element found at the given coordinates.

The 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
 

Assigns 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.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
 

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
    });
 }

Write the content of this N-dimensional array from the source buffer.

The size of the buffer must be equal or greater to the 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.