Indices

public final class Indices

Helper class for instantiating Index objects.

Public Constructors

Public Methods

static Index
all ()
An index that returns all elements of a dimension in the original order.
static Index
at ( NdArray <? extends Number> coord)
A coordinate that selects a specific element on a given dimension.
static Index
at (long coord, boolean keepDim)
A coordinate that selects a specific element on a given dimension.
static Index
at (long coord)
A coordinate that selects a specific element on a given dimension.
static Index
at ( NdArray <? extends Number> coord, boolean keepDim)
A coordinate that selects a specific element on a given dimension.
static Index
ellipsis ()
An index that expands to fill all available source dimensions.
static Index
even ()
An index that returns only elements found at an even position in the original dimension.
static Index
flip ()
An index that returns only elements on a given dimension between two coordinates.
static Index
hyperslab (long start, long stride, long count, long block)
An index that returns elements according to an hyperslab defined by start , stride , count , block .
static Index
newAxis ()
An index that inserts a new dimension of size 1 into the resulting array.
static Index
odd ()
An index that returns only elements found at an odd position in the original dimension.
static Index
range (long start, long end)
An index that returns only elements on a given dimension between two coordinates.
static Index
seq ( NdArray <? extends Number> coords)
An index that returns only specific elements on a given dimension.
static Index
seq (long... coords)
An index that returns only specific elements on a given dimension.
static Index
slice (long start, long end, long stride)
An index that returns every stride -th element between start and end .
static Index
slice (Long start, Long end)
An index that returns elements between start and end .
static Index
slice (long start, long end)
An index that returns elements between start and end .
static Index
slice (Long start, Long end, long stride)
An index that returns every stride -th element between start and end .
static Index
sliceFrom (long start)
An index that returns only elements on a given dimension starting at a specific coordinate.
static Index
sliceFrom (long start, long stride)
An index that returns only elements on a given dimension starting at a specific coordinate, using the given stride.
static Index
sliceTo (long end)
An index that returns only elements on a given dimension up to a specific coordinate.
static Index
sliceTo (long end, long stride)
An index that returns only elements on a given dimension up to a specific coordinate, using the given stride.
static Index
step (long stride)
An index that skips a fixed amount of coordinates between each values returned.

Inherited Methods

Public Constructors

public Indices ()

Public Methods

public static Index all ()

An index that returns all elements of a dimension in the original order.

Applying this index to a given dimension will return the original dimension directly.

For example, given a vector with n elements, all() returns x 0 , x 1 , ..., x n-1

Returns
  • index

public static Index at ( NdArray <? extends Number> coord)

A coordinate that selects a specific element on a given dimension.

This is equivalent to call at(long) but where the value of the coordinate is provided by an N-dimensional array.

Parameters
coord scalar indicating the coordinate of the element on the indexed axis
Returns
  • index
Throws
IllegalRankException if coord is not a scalar (rank 0)

public static Index at (long coord, boolean keepDim)

A coordinate that selects a specific element on a given dimension.

When this index is applied to a given dimension, the dimension is resolved as a single element and therefore, if keepDim is false, is excluded from the computation of the rank. If keepDim is true, the dimension is collapsed down to one element.

For example, given a 3D matrix on the axis [x, y, z], if matrix.slice(all(), at(0), at(0) , then the rank of the returned slice is 1 and its number of elements is x.numElements()

Parameters
coord coordinate of the element on the indexed axis
keepDim whether to remove the dimension.
Returns
  • index

public static Index at (long coord)

A coordinate that selects a specific element on a given dimension.

When this index is applied to a given dimension, the dimension is resolved as a single element and therefore is excluded from the computation of the rank.

For example, given a 3D matrix on the axis [x, y, z], if matrix.slice(all(), at(0), at(0) , then the rank of the returned slice is 1 and its number of elements is x.numElements()

Parameters
coord coordinate of the element on the indexed axis
Returns
  • index

public static Index at ( NdArray <? extends Number> coord, boolean keepDim)

A coordinate that selects a specific element on a given dimension.

This is equivalent to call at(long, boolean) but where the value of the coordinate is provided by an N-dimensional array.

If keepDim is true, the dimension is collapsed down to one element instead of being removed.

Parameters
coord scalar indicating the coordinate of the element on the indexed axis
keepDim whether to remove the dimension.
Returns
  • index
Throws
IllegalRankException if coord is not a scalar (rank 0)

public static Index ellipsis ()

An index that expands to fill all available source dimensions. Works the same as Python's ... .

Returns
  • index

public static Index even ()

An index that returns only elements found at an even position in the original dimension.

For example, given a vector with n elements on the x axis, and n is even, even() returns x 0 , x 2 , ..., x n-2

Returns
  • index

public static Index flip ()

An index that returns only elements on a given dimension between two coordinates.

For example, given a vector with n elements on the x axis, and n > k > j , range(j, k) returns x j , x j+1 , ..., x k

Returns
  • index

public static Index hyperslab (long start, long stride, long count, long block)

An index that returns elements according to an hyperslab defined by start , stride , count , block . See ERROR(/Hyperslab) .

Parameters
start Starting location for the hyperslab.
stride The number of elements to separate each element or block to be selected.
count The number of elements or blocks to select along the dimension.
block The size of the block selected from the dimension.
Returns
  • index

public static Index newAxis ()

An index that inserts a new dimension of size 1 into the resulting array.

Returns
  • index

public static Index odd ()

An index that returns only elements found at an odd position in the original dimension.

For example, given a vector with n elements on the x axis, and n is even, odd() returns x 1 , x 3 , ..., x n-1

Returns
  • index

public static Index range (long start, long end)

An index that returns only elements on a given dimension between two coordinates.

For example, given a vector with n elements on the x axis, and n > k > j , range(j, k) returns x j , x j+1 , ..., x k

Parameters
start coordinate of the first element of the sequence
end coordinate of the last element of the sequence (exclusive)
Returns
  • index

public static Index seq ( NdArray <? extends Number> coords)

An index that returns only specific elements on a given dimension.

This is equivalent to seq(long) but where the coordinates of the elements in the sequence are provided by an N-dimensional array.

Parameters
coords vector of coordinates of the elements in the sequence
Returns
  • index
Throws
IllegalRankException if coords is not a vector (rank 1)

public static Index seq (long... coords)

An index that returns only specific elements on a given dimension.

For example, given a vector with n elements on the x axis, and n > 10 , seq(8, 0, 3) returns x 8 , x 0 , x 3

Parameters
coords coordinates of the elements in the sequence
Returns
  • index

public static Index slice (long start, long end, long stride)

An index that returns every stride -th element between start and end . If start or end is null , starts or ends at the beginning or the end, respectively.

Analogous to Python's : slice syntax.

Returns
  • index

public static Index slice (Long start, Long end)

An index that returns elements between start and end . If start or end is null , starts or ends at the beginning or the end, respectively.

Analogous to Python's : slice syntax.

Returns
  • index

public static Index slice (long start, long end)

An index that returns elements between start and end . If start or end is null , starts or ends at the beginning or the end, respectively.

Analogous to Python's : slice syntax.

Returns
  • index

public static Index slice (Long start, Long end, long stride)

An index that returns every stride -th element between start and end . If start or end is null , starts or ends at the beginning or the end, respectively.

Analogous to Python's : slice syntax.

Returns
  • index

public static Index sliceFrom (long start)

An index that returns only elements on a given dimension starting at a specific coordinate.

For example, given a vector with n elements on the x axis, and n > k , from(k) returns x k , x k+1 , ..., x n-1

Parameters
start coordinate of the first element of the sequence
Returns
  • index

public static Index sliceFrom