Tensor

public final class Tensor

A statically typed multi-dimensional array whose elements are of a type described by T.

Instances of a Tensor are not thread-safe.

WARNING: Resources consumed by the Tensor object must be explicitly freed by invoking the close() method when the object is no longer needed. For example, using a try-with-resources block:

try (Tensor t = Tensor.create(...)) {
   doSomethingWith(t);
 }
 

Public Methods

boolean
booleanValue()
Returns the value in a scalar Boolean tensor.
byte[]
bytesValue()
Returns the value in a scalar String tensor.
void
close()
Release resources associated with the Tensor.
<U> U
copyTo(U dst)
Copies the contents of the tensor to dst and returns dst.
static Tensor<?>
create(Object obj)
Creates a tensor from an object whose class is inspected to figure out what the underlying data type should be.
static <T> Tensor<T>
create(Class<T> type, long[] shape, ByteBuffer data)
Create a Tensor of any type with data from the given buffer.
static Tensor<Double>
create(long[] shape, DoubleBuffer data)
Create a Double Tensor with data from the given buffer.
static Tensor<Long>
create(long[] shape, LongBuffer data)
Create an Long Tensor with data from the given buffer.
static Tensor<Integer>
create(long[] shape, IntBuffer data)
Create a Integer Tensor with data from the given buffer.
static Tensor<Float>
create(long[] shape, FloatBuffer data)
Create a Float Tensor with data from the given buffer.
static <T> Tensor<T>
create(Object obj, Class<T> type)
Creates a Tensor from a Java object.
DataType
dataType()
Returns the DataType of elements stored in the Tensor.
double
doubleValue()
Returns the value in a scalar Double tensor.
<U> Tensor<U>
expect(Class<U> type)
Returns this Tensor object with the type Tensor<U>.
float
floatValue()
Returns the value in a scalar Float tensor.
int
intValue()
Returns the value in a scalar Integer tensor.
long
longValue()
Returns the value in a scalar Long tensor.
int
numBytes()
Returns the size, in bytes, of the tensor data.
int
numDimensions()
Returns the number of dimensions (sometimes referred to as rank) of the Tensor.
int
numElements()
Returns the number of elements in a flattened (1-D) view of the tensor.
long[]
shape()
Returns the shape of the Tensor, i.e., the sizes of each dimension.
String
toString()
Returns a string describing the type and shape of the Tensor.
void
writeTo(LongBuffer dst)
Write the data of a Long tensor into the given buffer.
void
writeTo(DoubleBuffer dst)
Write the data of a Double tensor into the given buffer.
void
writeTo(IntBuffer dst)
Write the data of a Integer tensor into the given buffer.
void
writeTo(ByteBuffer dst)
Write the tensor data into the given buffer.
void
writeTo(FloatBuffer dst)
Write the data of a Float tensor into the given buffer.

Inherited Methods

Public Methods

public boolean booleanValue ()

Returns the value in a scalar Boolean tensor.

Throws
IllegalArgumentException if the Tensor does not represent a boolean scalar.

public byte[] bytesValue ()

Returns the value in a scalar String tensor.

Throws
IllegalArgumentException if the Tensor does not represent a boolean scalar.

public void close ()

Release resources associated with the Tensor.

WARNING:If not invoked, memory will be leaked.

The Tensor object is no longer usable after close returns.

public U copyTo (U dst)

Copies the contents of the tensor to dst and returns dst.

For non-scalar tensors, this method copies the contents of the underlying tensor to a Java array. For scalar tensors, use one of bytesValue(), floatValue(), doubleValue(), intValue(), longValue() or booleanValue() instead. The type and shape of dst must be compatible with the tensor. For example:

int matrix[2][2] = { {1,2},{3,4} };
 try(Tensor t = Tensor.create(matrix)) {
   // Succeeds and prints "3"
   int[][] copy = new int[2][2];
   System.out.println(t.copyTo(copy)[1][0]);

   // Throws IllegalArgumentException since the shape of dst does not match the shape of t.
   int[][] dst = new int[4][1];
   t.copyTo(dst);
 }
 

Parameters
dst
Throws
IllegalArgumentException if the tensor is a scalar or if dst is not compatible with the tensor (for example, mismatched data types or shapes).

public static Tensor<?> create (Object obj)

Creates a tensor from an object whose class is inspected to figure out what the underlying data type should be.

Parameters
obj
Throws
IllegalArgumentException if obj is not compatible with the TensorFlow type system.

public static Tensor<T> create (Class<T> type, long[] shape, ByteBuffer data)

Create a Tensor of any type with data from the given buffer.

Creates a Tensor with the provided shape of any type where the tensor's data has been encoded into data as per the specification of the TensorFlow C API.

Parameters
type the tensor element type, represented as a class object.
shape the tensor shape.
data a buffer containing the tensor data.
Throws
IllegalArgumentException If the tensor datatype or shape is not compatible with the buffer

public static Tensor<Double> create (long[] shape, DoubleBuffer data)

Create a Double Tensor with data from the given buffer.

Creates a Tensor with the given shape by copying elements from the buffer (starting from its current position) into the tensor. For example, if shape = {2,3} (which represents a 2x3 matrix) then the buffer must have 6 elements remaining, which will be consumed by this method.

Parameters
shape the tensor shape.
data a buffer containing the tensor data.
Throws
IllegalArgumentException If the tensor shape is not compatible with the buffer

public static Tensor<Long> create (long[] shape, LongBuffer data)

Create an Long Tensor with data from the given buffer.

Creates a Tensor with the given shape by copying elements from the buffer (starting from its current position) into the tensor. For example, if shape = {2,3} (which represents a 2x3 matrix) then the buffer must have 6 elements remaining, which will be consumed by this method.

Parameters
shape the tensor shape.
data a buffer containing the tensor data.
Throws
IllegalArgumentException If the tensor shape is not compatible with the buffer

public static Tensor<Integer> create (long[] shape, IntBuffer data)

Create a Integer Tensor with data from the given buffer.

Creates a Tensor with the given shape by copying elements from the buffer (starting from its current position) into the tensor. For example, if shape = {2,3} (which represents a 2x3 matrix) then the buffer must have 6 elements remaining, which will be consumed by this method.

Parameters
shape the tensor shape.
data a buffer containing the tensor data.
Throws
IllegalArgumentException If the tensor shape is not compatible with the buffer

public static Tensor<Float> create (long[] shape, FloatBuffer data)

Create a Float Tensor with data from the given buffer.

Creates a Tensor with the given shape by copying elements from the buffer (starting from its current position) into the tensor. For example, if shape = {2,3} (which represents a 2x3 matrix) then the buffer must have 6 elements remaining, which will be consumed by this method.

Parameters
shape the tensor shape.
data a buffer containing the tensor data.
Throws
IllegalArgumentException If the tensor shape is not compatible with the buffer

public static Tensor<T> create (Object obj, Class<T> type)

Creates a Tensor from a Java object.

A Tensor is a multi-dimensional array of elements of a limited set of types. Not all Java objects can be converted to a Tensor. In particular, the argument obj must be either a primitive (float, double, int, long, boolean, byte) or a multi-dimensional array of one of those primitives. The argument type specifies how to interpret the first argument as a TensorFlow type. For example:

// Valid: A 64-bit integer scalar.
 Tensor<Long> s = Tensor.create(42L, Long.class);

 // Valid: A 3x2 matrix of floats.
 float[][] matrix = new float[3][2];
 Tensor<Float> m = Tensor.create(matrix, Float.class);

 // Invalid: Will throw an IllegalArgumentException as an arbitrary Object
 // does not fit into the TensorFlow type system.
 Tensor<?> o = Tensor.create(new Object())

 // Invalid: Will throw an IllegalArgumentException since there are
 // a differing number of elements in each row of this 2-D array.
 int[][] twoD = new int[2][];
 twoD[0] = new int[1];
 twoD[1] = new int[2];
 Tensor<Integer> x = Tensor.create(twoD, Integer.class);
 
String-typed Tensors are multi-dimensional arrays of arbitrary byte sequences, so can be initialized from arrays of byte[] elements. For example:
// Valid: A String tensor.
 Tensor<String> s = Tensor.create(new byte[]{1, 2, 3}, String.class);

 // Java Strings will need to be encoded into a byte-sequence.
 String mystring = "foo";
 Tensor<String> s = Tensor.create(mystring.getBytes("UTF-8"), String.class);

 // Valid: Matrix of String tensors.
 // Each element might have a different length.
 byte[][][] matrix = new byte[2][2][];
 matrix[0][0] = "this".getBytes("UTF-8");
 matrix[0][1] = "is".getBytes("UTF-8");
 matrix[1][0] = "a".getBytes("UTF-8");
 matrix[1][1] = "matrix".getBytes("UTF-8");
 Tensor<String> m = Tensor.create(matrix, String.class);
 

Parameters
obj The object to convert to a Tensor<T>. Note that whether it is compatible with the type T is not checked by the type system. For type-safe creation of tensors, use Tensors.
type The class object representing the type T.
Throws
IllegalArgumentException if obj is not compatible with the TensorFlow type system.

public DataType dataType ()

Returns the DataType of elements stored in the Tensor.

public double doubleValue ()

Returns the value in a scalar Double tensor.

Throws
IllegalArgumentException if the Tensor does not represent a double scalar.

public Tensor<U> expect (Class<U> type)

Returns this Tensor object with the type Tensor<U>. This method is useful when given a value of type Tensor<?>.

Parameters
type any (non-null) array of the correct type.
Throws
IllegalArgumentException if the actual data type of this object does not match the type U.

public float floatValue ()

Returns the value in a scalar Float tensor.

Throws
IllegalArgumentException if the Tensor does not represent a float scalar.

public int intValue ()

Returns the value in a scalar Integer tensor.

Throws
IllegalArgumentException if the Tensor does not represent a int scalar.

public long longValue ()

Returns the value in a scalar Long tensor.

Throws
IllegalArgumentException if the Tensor does not represent a long scalar.

public int numBytes ()

Returns the size, in bytes, of the tensor data.

public int numDimensions ()

Returns the number of dimensions (sometimes referred to as rank) of the Tensor.

Will be 0 for a scalar, 1 for a vector, 2 for a matrix, 3 for a 3-dimensional tensor etc.

public int numElements ()

Returns the number of elements in a flattened (1-D) view of the tensor.

public long[] shape ()

Returns the shape of the Tensor, i.e., the sizes of each dimension.

Returns
  • an array where the i-th element is the size of the i-th dimension of the tensor.

public String toString ()

Returns a string describing the type and shape of the Tensor.

public void writeTo (LongBuffer dst)

Write the data of a Long tensor into the given buffer.

Copies numElements() elements to the buffer.

Parameters
dst the destination buffer
Throws
BufferOverflowException If there is insufficient space in the given buffer for the data in this tensor
IllegalArgumentException If the tensor datatype is not Long

public void writeTo (DoubleBuffer dst)

Write the data of a Double tensor into the given buffer.

Copies numElements() elements to the buffer.

Parameters
dst the destination buffer
Throws
BufferOverflowException If there is insufficient space in the given buffer for the data in this tensor
IllegalArgumentException If the tensor datatype is not Double

public void writeTo (IntBuffer dst)

Write the data of a Integer tensor into the given buffer.

Copies numElements() elements to the buffer.

Parameters
dst the destination buffer
Throws
BufferOverflowException If there is insufficient space in the given buffer for the data in this tensor
IllegalArgumentException If the tensor data type is not Integer

public void writeTo (ByteBuffer dst)

Write the tensor data into the given buffer.

Copies numBytes() bytes to the buffer in native byte order for primitive types.

Parameters
dst the destination buffer
Throws
BufferOverflowException If there is insufficient space in the given buffer for the data in this tensor

public void writeTo (FloatBuffer dst)

Write the data of a Float tensor into the given buffer.

Copies numElements() elements to the buffer.

Parameters
dst the destination buffer
Throws
BufferOverflowException If there is insufficient space in the given buffer for the data in this tensor
IllegalArgumentException If the tensor datatype is not Float