目录
Class Tensor
__init__
Properties
device
dtype
graph
name
op
shape
Methods
1、__abs__
2、__add__
3、__and__
4、__bool__
5、__div__
6、__eq__
7、__floordiv__
8、__ge__
9、__getitem__
10、__gt__
10、__invert__
11、__iter__
12、__le__
13、__len__
14、__lt__
15、__matmul__
16、__mod__
17、__mul__
18、__ne__
19、__neg__
20、__nonzero__
21、__or__
22、__pow__
23、__radd__
24、__rand__
25、__rdiv__
26、__rfloordiv__
27、__rmatmul__
28、__rmod__
29、__rmul__
30、__ror__
31、__rpow__
32、__rsub__
33、__rtruediv__
34、__rxor__
35、__sub__
36、__truediv__
37、__xor__
38、consumers
39、eval
40、experimental_ref
41、get_shape
42、set_shape
Class Tensor
Represents one of the outputs of an Operation.
Aliases:
- Class tf.compat.v1.Tensor
- Class tf.compat.v2.Tensor
A Tensor is a symbolic handle to one of the outputs of an Operation. It does not hold the values of that operation's output, but instead provides a means of computing those values in a TensorFlow tf.compat.v1.Session.
This class has two primary purposes:
- A
Tensorcan be passed as an input to anotherOperation. This builds a dataflow connection between operations, which enables TensorFlow to execute an entireGraphthat represents a large, multi-step computation. - After the graph has been launched in a session, the value of the
Tensorcan be computed by passing it totf.Session.run.t.eval()is a shortcut for callingtf.compat.v1.get_default_session().run(t).
In the following example, c, d, and e are symbolic Tensor objects, whereas result is a numpy array that stores a concrete value:
# Build a dataflow graph.
c = tf.constant([[1.0, 2.0], [3.0, 4.0]])
d = tf.constant([[1.0, 1.0], [0.0, 1.0]])
e = tf.matmul(c, d)
# Construct a `Session` to execute the graph.
sess = tf.compat.v1.Session()
# Execute the graph and store the value that `e` represents in `result`.
result = sess.run(e)__init__
View source
代码语言:javascript复制__init__(
op,
value_index,
dtype
)Creates a new Tensor.
Args:
op: AnOperation.Operationthat computes this tensor.value_index: Anint. Index of the operation's endpoint that produces this tensor.dtype: ADType. Type of elements stored in this tensor.
Raises:
TypeError: If the op is not anOperation.
Properties
device
The name of the device on which this tensor will be produced, or None.
dtype
The DType of elements in this tensor.
graph
The Graph that contains this tensor.
name
The string name of this tensor.
op
The Operation that produces this tensor as an output.
shape
Returns the TensorShape that represents the shape of this tensor.
The shape is computed using shape inference functions that are registered in the Op for each Operation. See tf.TensorShape for more details of what a shape represents.
The inferred shape of a tensor is used to provide shape information without having to launch the graph in a session. This can be used for debugging, and providing early error messages. For example:
代码语言:javascript复制c = tf.constant([[1.0, 2.0, 3.0], [4.0, 5.0, 6.0]])
print(c.shape)
==> TensorShape([Dimension(2), Dimension(3)])
d = tf.constant([[1.0, 0.0], [0.0, 1.0], [1.0, 0.0], [0.0, 1.0]])
print(d.shape)
==> TensorShape([Dimension(4), Dimension(2)])
# Raises a ValueError, because `c` and `d` do not have compatible
# inner dimensions.
e = tf.matmul(c, d)
f = tf.matmul(c, d, transpose_a=True, transpose_b=True)
print(f.shape)
==> TensorShape([Dimension(3), Dimension(4)])In some cases, the inferred shape may have unknown dimensions. If the caller has additional information about the values of these dimensions, Tensor.set_shape() can be used to augment the inferred shape.
Returns:
A TensorShape representing the shape of this tensor.
value_index
The index of this tensor in the outputs of its Operation.
Methods
1、__abs__
View source
代码语言:javascript复制__abs__(
x,
name=None
)Computes the absolute value of a tensor.Given a tensor of integer or floating-point values, this operation returns a tensor of the same type, where each element contains the absolute value of the corresponding element in the input.Given a tensor x of complex numbers, this operation returns a tensor of type float32 or float64 that is the absolute value of each element in x. All elements in x must be complex numbers of the form. The absolute value is computed as. For example:
x = tf.constant([[-2.25 4.75j], [-3.25 5.75j]])
tf.abs(x) # [5.25594902, 6.60492229]Args:
x: ATensororSparseTensorof typefloat16,float32,float64,int32,int64,complex64orcomplex128.name: A name for the operation (optional).
Returns:
- A
TensororSparseTensorthe same size, type, and sparsity asxwith absolute values. Note, forcomplex64orcomplex128input, the returnedTensorwill be of typefloat32orfloat64, respectively.
If x is a SparseTensor, returns SparseTensor(x.indices, tf.math.abs(x.values, ...), x.dense_shape)
2、__add__
View source
代码语言:javascript复制__add__(
x,
y
)Dispatches to add for strings and add_v2 for all other types.
3、__and__
View source
代码语言:javascript复制__and__(
x,
y
)Returns the truth value of x AND y element-wise.
NOTE: math.logical_and supports broadcasting. More about broadcasting here
Args:
x: ATensorof typebool.y: ATensorof typebool.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
4、__bool__
View source
代码语言:javascript复制__bool__()Dummy method to prevent a tensor from being used as a Python bool.
This overload raises a TypeError when the user inadvertently treats a Tensor as a boolean (most commonly in an if or while statement), in code that was not converted by AutoGraph. For example:
if tf.constant(True): # Will raise.
# ...
if tf.constant(5) < tf.constant(7): # Will raise.
# ...Raises:
TypeError.
5、__div__
View source
代码语言:javascript复制__div__(
x,
y
)Divide two values using Python 2 semantics.
Used for Tensor.div.
Args:
x:Tensornumerator of real numeric type.y:Tensordenominator of real numeric type.name: A name for the operation (optional).
Returns:
x / yreturns the quotient of x and y.
6、__eq__
View source
代码语言:javascript复制__eq__(other)Compares two tensors element-wise for equality.
7、__floordiv__
View source
代码语言:javascript复制__floordiv__(
x,
y
)Divides x / y elementwise, rounding toward the most negative integer.
The same as tf.compat.v1.div(x,y) for integers, but uses tf.floor(tf.compat.v1.div(x,y)) for floating point arguments so that the result is always an integer (though possibly an integer represented as floating point). This op is generated by x // y floor division in Python 3 and in Python 2.7 with from __future__ import division.
x and y must have the same type, and the result will have the same type as well.
Args:
x:Tensornumerator of real numeric type.y:Tensordenominator of real numeric type.name: A name for the operation (optional).
Returns:
x / yrounded down.
Raises:
TypeError: If the inputs are complex.
8、__ge__
Defined in generated file: python/ops/gen_math_ops.py
__ge__(
x,
y,
name=None
)Returns the truth value of (x >= y) element-wise.
NOTE: math.greater_equal supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:float32,float64,int32,uint8,int16,int8,int64,bfloat16,uint16,half,uint32,uint64.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
9、__getitem__
View source
代码语言:javascript复制__getitem__(
tensor,
slice_spec,
var=None
)Overload for Tensor.getitem.
This operation extracts the specified region from the tensor. The notation is similar to NumPy with the restriction that currently only support basic indexing. That means that using a non-scalar tensor as input is not currently allowed.
Some useful examples:
代码语言:javascript复制# Strip leading and trailing 2 elements
foo = tf.constant([1,2,3,4,5,6])
print(foo[2:-2].eval()) # => [3,4]
# Skip every other row and reverse the order of the columns
foo = tf.constant([[1,2,3], [4,5,6], [7,8,9]])
print(foo[::2,::-1].eval()) # => [[3,2,1], [9,8,7]]
# Use scalar tensors as indices on both dimensions
print(foo[tf.constant(0), tf.constant(2)].eval()) # => 3
# Insert another dimension
foo = tf.constant([[1,2,3], [4,5,6], [7,8,9]])
print(foo[tf.newaxis, :, :].eval()) # => [[[1,2,3], [4,5,6], [7,8,9]]]
print(foo[:, tf.newaxis, :].eval()) # => [[[1,2,3]], [[4,5,6]], [[7,8,9]]]
print(foo[:, :, tf.newaxis].eval()) # => [[[1],[2],[3]], [[4],[5],[6]],
[[7],[8],[9]]]
# Ellipses (3 equivalent operations)
foo = tf.constant([[1,2,3], [4,5,6], [7,8,9]])
print(foo[tf.newaxis, :, :].eval()) # => [[[1,2,3], [4,5,6], [7,8,9]]]
print(foo[tf.newaxis, ...].eval()) # => [[[1,2,3], [4,5,6], [7,8,9]]]
print(foo[tf.newaxis].eval()) # => [[[1,2,3], [4,5,6], [7,8,9]]]
# Masks
foo = tf.constant([[1,2,3], [4,5,6], [7,8,9]])
print(foo[foo > 2].eval()) # => [3, 4, 5, 6, 7, 8, 9]Notes:
tf.newaxisisNoneas in NumPy.- An implicit ellipsis is placed at the end of the
slice_spec - NumPy advanced indexing is currently not supported.
Args:
tensor: An ops.Tensor object.slice_spec: The arguments to Tensor.getitem.var: In the case of variable slice assignment, the Variable object to slice (i.e. tensor is the read-only view of this variable).
Returns:
- The appropriate slice of "tensor", based on "slice_spec".
Raises:
ValueError: If a slice range is negative size.TypeError: If the slice indices aren't int, slice, ellipsis, tf.newaxis or scalar int32/int64 tensors.
10、__gt__
Defined in generated file: python/ops/gen_math_ops.py
__gt__(
x,
y,
name=None
)Returns the truth value of (x > y) element-wise.
NOTE: math.greater supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:float32,float64,int32,uint8,int16,int8,int64,bfloat16,uint16,half,uint32,uint64.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
10、__invert__
Defined in generated file: python/ops/gen_math_ops.py
__invert__(
x,
name=None
)Returns the truth value of NOT x element-wise.
Args:
x: ATensorof typebool.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
11、__iter__
View source
代码语言:javascript复制__iter__()12、__le__
Defined in generated file: python/ops/gen_math_ops.py
__le__(
x,
y,
name=None
)Returns the truth value of (x <= y) element-wise.
NOTE: math.less_equal supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:float32,float64,int32,uint8,int16,int8,int64,bfloat16,uint16,half,uint32,uint64.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
13、__len__
View source
代码语言:javascript复制__len__()14、__lt__
Defined in generated file: python/ops/gen_math_ops.py
__lt__(
x,
y,
name=None
)Returns the truth value of (x < y) element-wise.
NOTE: math.less supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:float32,float64,int32,uint8,int16,int8,int64,bfloat16,uint16,half,uint32,uint64.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
15、__matmul__
View source
代码语言:javascript复制__matmul__(
x,
y
)Multiplies matrix a by matrix b, producing a * b.
The inputs must, following any transpositions, be tensors of rank >= 2 where the inner 2 dimensions specify valid matrix multiplication arguments, and any further outer dimensions match.
Both matrices must be of the same type. The supported types are: float16, float32, float64, int32, complex64, complex128.
Either matrix can be transposed or adjointed (conjugated and transposed) on the fly by setting one of the corresponding flag to True. These are False by default.
If one or both of the matrices contain a lot of zeros, a more efficient multiplication algorithm can be used by setting the corresponding a_is_sparse or b_is_sparse flag to True. These are False by default. This optimization is only available for plain matrices (rank-2 tensors) with datatypes bfloat16 or float32.
For example:
代码语言:javascript复制# 2-D tensor `a`
# [[1, 2, 3],
# [4, 5, 6]]
a = tf.constant([1, 2, 3, 4, 5, 6], shape=[2, 3])
# 2-D tensor `b`
# [[ 7, 8],
# [ 9, 10],
# [11, 12]]
b = tf.constant([7, 8, 9, 10, 11, 12], shape=[3, 2])
# `a` * `b`
# [[ 58, 64],
# [139, 154]]
c = tf.matmul(a, b)
# 3-D tensor `a`
# [[[ 1, 2, 3],
# [ 4, 5, 6]],
# [[ 7, 8, 9],
# [10, 11, 12]]]
a = tf.constant(np.arange(1, 13, dtype=np.int32),
shape=[2, 2, 3])
# 3-D tensor `b`
# [[[13, 14],
# [15, 16],
# [17, 18]],
# [[19, 20],
# [21, 22],
# [23, 24]]]
b = tf.constant(np.arange(13, 25, dtype=np.int32),
shape=[2, 3, 2])
# `a` * `b`
# [[[ 94, 100],
# [229, 244]],
# [[508, 532],
# [697, 730]]]
c = tf.matmul(a, b)
# Since python >= 3.5 the @ operator is supported (see PEP 465).
# In TensorFlow, it simply calls the `tf.matmul()` function, so the
# following lines are equivalent:
d = a @ b @ [[10.], [11.]]
d = tf.matmul(tf.matmul(a, b), [[10.], [11.]])Args:
a:Tensorof typefloat16,float32,float64,int32,complex64,complex128and rank > 1.b:Tensorwith same type and rank asa.transpose_a: IfTrue,ais transposed before multiplication.transpose_b: IfTrue,bis transposed before multiplication.adjoint_a: IfTrue,ais conjugated and transposed before multiplication.adjoint_b: IfTrue,bis conjugated and transposed before multiplication.a_is_sparse: IfTrue,ais treated as a sparse matrix.b_is_sparse: IfTrue,bis treated as a sparse matrix.name: Name for the operation (optional).
Returns:
- A
Tensorof the same type asaandbwhere each inner-most matrix is the product of the corresponding matrices inaandb, e.g. if all transpose or adjoint attributes areFalse:output[..., i, j] = sum_k (a[..., i, k] *b[..., k, j]), for all indices i, j.Note: This is matrix product, not element-wise product.
Raises:
ValueError: If transpose_a and adjoint_a, or transpose_b and adjoint_b are both set to True.
16、__mod__
View source
代码语言:javascript复制__mod__(
x,
y
)Returns element-wise remainder of division. When x < 0 xor y < 0 is
true, this follows Python semantics in that the result here is consistent with a flooring divide. E.g. floor(x / y) * y mod(x, y) = x.
NOTE: math.floormod supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:int32,int64,bfloat16,half,float32,float64.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensor. Has the same type asx.
17、__mul__
View source
代码语言:javascript复制__mul__(
x,
y
)Dispatches cwise mul for "DenseDense" and "DenseSparse".
18、__ne__
View source
代码语言:javascript复制__ne__(other)Compares two tensors element-wise for equality.
19、__neg__
Defined in generated file: python/ops/gen_math_ops.py
__neg__(
x,
name=None
)Computes numerical negative value element-wise.
I.e.,
Args:
x: ATensor. Must be one of the following types:bfloat16,half,float32,float64,int32,int64,complex64,complex128.name: A name for the operation (optional).
Returns:
- A
Tensor. Has the same type asx.Ifxis aSparseTensor, returnsSparseTensor(x.indices, tf.math.negative(x.values, ...), x.dense_shape)
20、__nonzero__
View source
代码语言:javascript复制__nonzero__()Dummy method to prevent a tensor from being used as a Python bool.
This is the Python 2.x counterpart to __bool__() above.
Raises:
TypeError.
21、__or__
View source
代码语言:javascript复制__or__(
x,
y
)Returns the truth value of x OR y element-wise.
NOTE: math.logical_or supports broadcasting. More about broadcasting here
Args:
x: ATensorof typebool.y: ATensorof typebool.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
22、__pow__
View source
代码语言:javascript复制__pow__(
x,
y
)Computes the power of one value to another.
Given a tensor x and a tensor y, this operation computes
for corresponding elements in x and y. For example:
x = tf.constant([[2, 2], [3, 3]])
y = tf.constant([[8, 16], [2, 3]])
tf.pow(x, y) # [[256, 65536], [9, 27]]Args:
x: ATensorof typefloat16,float32,float64,int32,int64,complex64, orcomplex128.y: ATensorof typefloat16,float32,float64,int32,int64,complex64, orcomplex128.name: A name for the operation (optional).
Returns:
- A
Tensor.
23、__radd__
View source
代码语言:javascript复制__radd__(
y,
x
)Dispatches to add for strings and add_v2 for all other types.
24、__rand__
View source
代码语言:javascript复制__rand__(
y,
x
)Returns the truth value of x AND y element-wise.
NOTE: math.logical_and supports broadcasting. More about broadcasting here
Args:
x: ATensorof typebool.y: ATensorof typebool.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
25、__rdiv__
View source
代码语言:javascript复制__rdiv__(
y,
x
)Divide two values using Python 2 semantics.
Used for Tensor.div.
Args:
x:Tensornumerator of real numeric type.y:Tensordenominator of real numeric type.name: A name for the operation (optional).
Returns:
x / yreturns the quotient of x and y.
26、__rfloordiv__
View source
代码语言:javascript复制__rfloordiv__(
y,
x
)Divides x / y elementwise, rounding toward the most negative integer.
The same as tf.compat.v1.div(x,y) for integers, but uses tf.floor(tf.compat.v1.div(x,y)) for floating point arguments so that the result is always an integer (though possibly an integer represented as floating point). This op is generated by x // y floor division in Python 3 and in Python 2.7 with from __future__ import division.
x and y must have the same type, and the result will have the same type as well.
Args:
x:Tensornumerator of real numeric type.y:Tensordenominator of real numeric type.name: A name for the operation (optional).
Returns:
x / yrounded down.
Raises:
TypeError: If the inputs are complex.
27、__rmatmul__
View source
代码语言:javascript复制__rmatmul__(
y,
x
)Multiplies matrix a by matrix b, producing a * b.
The inputs must, following any transpositions, be tensors of rank >= 2 where the inner 2 dimensions specify valid matrix multiplication arguments, and any further outer dimensions match.
Both matrices must be of the same type. The supported types are: float16, float32, float64, int32, complex64, complex128.
Either matrix can be transposed or adjointed (conjugated and transposed) on the fly by setting one of the corresponding flag to True. These are False by default.
If one or both of the matrices contain a lot of zeros, a more efficient multiplication algorithm can be used by setting the corresponding a_is_sparse or b_is_sparse flag to True. These are False by default. This optimization is only available for plain matrices (rank-2 tensors) with datatypes bfloat16 or float32.
For example:
Args:
a:Tensorof typefloat16,float32,float64,int32,complex64,complex128and rank > 1.b:Tensorwith same type and rank asa.transpose_a: IfTrue,ais transposed before multiplication.transpose_b: IfTrue,bis transposed before multiplication.adjoint_a: IfTrue,ais conjugated and transposed before multiplication.adjoint_b: IfTrue,bis conjugated and transposed before multiplication.a_is_sparse: IfTrue,ais treated as a sparse matrix.b_is_sparse: IfTrue,bis treated as a sparse matrix.name: Name for the operation (optional).
Returns:
- A
Tensorof the same type asaandbwhere each inner-most matrix is the product of the corresponding matrices inaandb, e.g. if all transpose or adjoint attributes areFalse:output[..., i, j] = sum_k (a[..., i, k] *b[..., k, j]), for all indices i, j.Note: This is matrix product, not element-wise product.
Raises:
ValueError: If transpose_a and adjoint_a, or transpose_b and adjoint_b are both set to True.
28、__rmod__
View source
代码语言:javascript复制__rmod__(
y,
x
)Returns element-wise remainder of division. When x < 0 xor y < 0 is
true, this follows Python semantics in that the result here is consistent with a flooring divide. E.g. floor(x / y) * y mod(x, y) = x.
NOTE: math.floormod supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:int32,int64,bfloat16,half,float32,float64.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensor. Has the same type asx.
29、__rmul__
View source
代码语言:javascript复制__rmul__(
y,
x
)Dispatches cwise mul for "DenseDense" and "DenseSparse".
30、__ror__
View source
代码语言:javascript复制__ror__(
y,
x
)Returns the truth value of x OR y element-wise.
NOTE: math.logical_or supports broadcasting. More about broadcasting here
Args:
x: ATensorof typebool.y: ATensorof typebool.name: A name for the operation (optional).
Returns:
- A
Tensorof typebool.
31、__rpow__
View source
代码语言:javascript复制__rpow__(
y,
x
)Computes the power of one value to another.
Given a tensor x and a tensor y, this operation computes
for corresponding elements in x and y. For example:
x = tf.constant([[2, 2], [3, 3]])
y = tf.constant([[8, 16], [2, 3]])
tf.pow(x, y) # [[256, 65536], [9, 27]]Args:
x: ATensorof typefloat16,float32,float64,int32,int64,complex64, orcomplex128.y: ATensorof typefloat16,float32,float64,int32,int64,complex64, orcomplex128.name: A name for the operation (optional).
Returns:
- A
Tensor.
32、__rsub__
View source
代码语言:javascript复制__rsub__(
y,
x
)Returns x - y element-wise.
NOTE: Subtract supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:bfloat16,half,float32,float64,uint8,int8,uint16,int16,int32,int64,complex64,complex128.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensor. Has the same type asx.
33、__rtruediv__
View source
代码语言:javascript复制__rtruediv__(
y,
x
)34、__rxor__
View source
代码语言:javascript复制__rxor__(
y,
x
)Logical XOR function.
x ^ y = (x | y) & ~(x & y)
Inputs are tensor and if the tensors contains more than one element, an element-wise logical XOR is computed.
Usage:
代码语言:javascript复制x = tf.constant([False, False, True, True], dtype = tf.bool)
y = tf.constant([False, True, False, True], dtype = tf.bool)
z = tf.logical_xor(x, y, name="LogicalXor")
# here z = [False True True False]Args:
x: ATensortype bool.y: ATensorof type bool.
Returns:
- A
Tensorof type bool with the same size as that of x or y.
35、__sub__
View source
代码语言:javascript复制__sub__(
x,
y
)Returns x - y element-wise.
NOTE: Subtract supports broadcasting. More about broadcasting here
Args:
x: ATensor. Must be one of the following types:bfloat16,half,float32,float64,uint8,int8,uint16,int16,int32,int64,complex64,complex128.y: ATensor. Must have the same type asx.name: A name for the operation (optional).
Returns:
- A
Tensor. Has the same type asx.
36、__truediv__
View source
代码语言:javascript复制__truediv__(
x,
y
)37、__xor__
View source
代码语言:javascript复制__xor__(
x,
y
)Logical XOR function.
x ^ y = (x | y) & ~(x & y)
Inputs are tensor and if the tensors contains more than one element, an element-wise logical XOR is computed.
Usage:
代码语言:javascript复制x = tf.constant([False, False, True, True], dtype = tf.bool)
y = tf.constant([False, True, False, True], dtype = tf.bool)
z = tf.logical_xor(x, y, name="LogicalXor")
# here z = [False True True False]Args:
x: ATensortype bool.y: ATensorof type bool.
Returns:
- A
Tensorof type bool with the same size as that of x or y.
38、consumers
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代码语言:javascript复制consumers()Returns a list of Operations that consume this tensor.
Returns:
A list of Operations.
39、eval
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代码语言:javascript复制eval(
feed_dict=None,
session=None
)Evaluates this tensor in a Session.Calling this method will execute all preceding operations that produce the inputs needed for the operation that produces this tensor.
N.B. Before invoking Tensor.eval(), its graph must have been launched in a session, and either a default session must be available, or session must be specified explicitly.
Args:
feed_dict: A dictionary that mapsTensorobjects to feed values. Seetf.Session.runfor a description of the valid feed values.session: (Optional.) TheSessionto be used to evaluate this tensor. If none, the default session will be used.
Returns:
- A numpy array corresponding to the value of this tensor.
例:
代码语言:javascript复制import tensorflow as tf
a=tf.constant([1.0,2.0],name="a")
b=tf.constant([2.0,3.0],name="b")
c=tf.add(a,b,name="sum")
print(c)
sess=tf.Session()
with sess.as_default():
print(c.eval())
Output:
--------------------------------------------
Tensor(“sum:0”, shape=(2,), dtype=float32)
[ 3. 5.]
--------------------------------------------40、experimental_ref
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代码语言:javascript复制experimental_ref()Returns a hashable reference object to this Tensor.
Warning: Experimental API that could be changed or removed.
The primary usecase for this API is to put tensors in a set/dictionary. We can't put tensors in a set/dictionary as tensor.__hash__() is no longer available starting Tensorflow 2.0.
import tensorflow as tf
x = tf.constant(5)
y = tf.constant(10)
z = tf.constant(10)
# The followings will raise an exception starting 2.0
# TypeError: Tensor is unhashable if Tensor equality is enabled.
tensor_set = {x, y, z}
tensor_dict = {x: 'five', y: 'ten', z: 'ten'}Instead, we can use tensor.experimental_ref().
tensor_set = {x.experimental_ref(),
y.experimental_ref(),
z.experimental_ref()}
print(x.experimental_ref() in tensor_set)
==> True
tensor_dict = {x.experimental_ref(): 'five',
y.experimental_ref(): 'ten',
z.experimental_ref(): 'ten'}
print(tensor_dict[y.experimental_ref()])
==> tenAlso, the reference object provides .deref() function that returns the original Tensor.
x = tf.constant(5)
print(x.experimental_ref().deref())
==> tf.Tensor(5, shape=(), dtype=int32)41、get_shape
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代码语言:javascript复制get_shape()Alias of Tensor.shape.
42、set_shape
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代码语言:javascript复制set_shape(shape)Updates the shape of this tensor.
This method can be called multiple times, and will merge the given shape with the current shape of this tensor. It can be used to provide additional information about the shape of this tensor that cannot be inferred from the graph alone. For example, this can be used to provide additional information about the shapes of images:
_, image_data = tf.compat.v1.TFRecordReader(...).read(...)
image = tf.image.decode_png(image_data, channels=3)
# The height and width dimensions of `image` are data dependent, and
# cannot be computed without executing the op.
print(image.shape)
==> TensorShape([Dimension(None), Dimension(None), Dimension(3)])
# We know that each image in this dataset is 28 x 28 pixels.
image.set_shape([28, 28, 3])
print(image.shape)
==> TensorShape([Dimension(28), Dimension(28), Dimension(3)])NOTE: This shape is not enforced at runtime. Setting incorrect shapes can result in inconsistencies between the statically-known graph and the runtime value of tensors. For runtime validation of the shape, use tf.ensure_shape instead.
Args:
shape: ATensorShaperepresenting the shape of this tensor, aTensorShapeProto, a list, a tuple, or None.
Raises:
ValueError: Ifshapeis not compatible with the current shape of this tensor.


