TensorFlow 2 version | View source on GitHub |
See the Variables Guide.
Inherits From: Variable
tf.Variable(
initial_value=None, trainable=None, collections=None, validate_shape=True,
caching_device=None, name=None, variable_def=None, dtype=None,
expected_shape=None, import_scope=None, constraint=None, use_resource=None,
synchronization=tf.VariableSynchronization.AUTO,
aggregation=tf.VariableAggregation.NONE, shape=None
)
A variable maintains state in the graph across calls to run()
. You add a
variable to the graph by constructing an instance of the class Variable
.
The Variable()
constructor requires an initial value for the variable,
which can be a Tensor
of any type and shape. The initial value defines the
type and shape of the variable. After construction, the type and shape of
the variable are fixed. The value can be changed using one of the assign
methods.
If you want to change the shape of a variable later you have to use an
assign
Op with validate_shape=False
.
Just like any Tensor
, variables created with Variable()
can be used as
inputs for other Ops in the graph. Additionally, all the operators
overloaded for the Tensor
class are carried over to variables, so you can
also add nodes to the graph by just doing arithmetic on variables.
import tensorflow as tf
# Create a variable.
w = tf.Variable(<initial-value>, name=<optional-name>)
# Use the variable in the graph like any Tensor.
y = tf.matmul(w, ...another variable or tensor...)
# The overloaded operators are available too.
z = tf.sigmoid(w + y)
# Assign a new value to the variable with `assign()` or a related method.
w.assign(w + 1.0)
w.assign_add(1.0)
When you launch the graph, variables have to be explicitly initialized before
you can run Ops that use their value. You can initialize a variable by
running its initializer op, restoring the variable from a save file, or
simply running an assign
Op that assigns a value to the variable. In fact,
the variable initializer op is just an assign
Op that assigns the
variable's initial value to the variable itself.
# Launch the graph in a session.
with tf.compat.v1.Session() as sess:
# Run the variable initializer.
sess.run(w.initializer)
# ...you now can run ops that use the value of 'w'...
The most common initialization pattern is to use the convenience function
global_variables_initializer()
to add an Op to the graph that initializes
all the variables. You then run that Op after launching the graph.
# Add an Op to initialize global variables.
init_op = tf.compat.v1.global_variables_initializer()
# Launch the graph in a session.
with tf.compat.v1.Session() as sess:
# Run the Op that initializes global variables.
sess.run(init_op)
# ...you can now run any Op that uses variable values...
If you need to create a variable with an initial value dependent on another
variable, use the other variable's initialized_value()
. This ensures that
variables are initialized in the right order.
All variables are automatically collected in the graph where they are
created. By default, the constructor adds the new variable to the graph
collection GraphKeys.GLOBAL_VARIABLES
. The convenience function
global_variables()
returns the contents of that collection.
When building a machine learning model it is often convenient to distinguish
between variables holding the trainable model parameters and other variables
such as a global step
variable used to count training steps. To make this
easier, the variable constructor supports a trainable=<bool>
parameter. If
True
, the new variable is also added to the graph collection
GraphKeys.TRAINABLE_VARIABLES
. The convenience function
trainable_variables()
returns the contents of this collection. The
various Optimizer
classes use this collection as the default list of
variables to optimize.
v = tf.Variable(True)
tf.cond(v, lambda: v.assign(False), my_false_fn) # Note: this is broken.
Here, adding use_resource=True
when constructing the variable will
fix any nondeterminism issues:
v = tf.Variable(True, use_resource=True)
tf.cond(v, lambda: v.assign(False), my_false_fn)
To use the replacement for variables which does not have these issues:
- Add
use_resource=True
when constructingtf.Variable
; - Call
tf.compat.v1.get_variable_scope().set_use_resource(True)
inside atf.compat.v1.variable_scope
before thetf.compat.v1.get_variable()
call.
Args | |
---|---|
initial_value
|
A Tensor , or Python object convertible to a Tensor ,
which is the initial value for the Variable. The initial value must have
a shape specified unless validate_shape is set to False. Can also be a
callable with no argument that returns the initial value when called. In
that case, dtype must be specified. (Note that initializer functions
from init_ops.py must first be bound to a shape before being used here.)
|
trainable
|
If True , also adds the variable to the graph collection
GraphKeys.TRAINABLE_VARIABLES . This collection is used as the default
list of variables to use by the Optimizer classes. Defaults to True ,
unless synchronization is set to ON_READ , in which case it defaults
to False .
|
collections
|
List of graph collections keys. The new variable is added to
these collections. Defaults to [GraphKeys.GLOBAL_VARIABLES] .
|
validate_shape
|
If False , allows the variable to be initialized with a
value of unknown shape. If True , the default, the shape of
initial_value must be known.
|
caching_device
|
Optional device string describing where the Variable
should be cached for reading. Defaults to the Variable's device. If not
None , caches on another device. Typical use is to cache on the device
where the Ops using the Variable reside, to deduplicate copying through
Switch and other conditional statements.
|
name
|
Optional name for the variable. Defaults to 'Variable' and gets
uniquified automatically.
|
variable_def
|
VariableDef protocol buffer. If not None , recreates the
Variable object with its contents, referencing the variable's nodes in
the graph, which must already exist. The graph is not changed.
variable_def and the other arguments are mutually exclusive.
|
dtype
|
If set, initial_value will be converted to the given type. If
None , either the datatype will be kept (if initial_value is a
Tensor), or convert_to_tensor will decide.
|
expected_shape
|
A TensorShape. If set, initial_value is expected to have this shape. |
import_scope
|
Optional string . Name scope to add to the Variable. Only
used when initializing from protocol buffer.
|
constraint
|
An optional projection function to be applied to the variable
after being updated by an Optimizer (e.g. used to implement norm
constraints or value constraints for layer weights). The function must
take as input the unprojected Tensor representing the value of the
variable and return the Tensor for the projected value (which must have
the same shape). Constraints are not safe to use when doing asynchronous
distributed training.
|
use_resource
|
whether to use resource variables. |
synchronization
|
Indicates when a distributed a variable will be
aggregated. Accepted values are constants defined in the class
tf.VariableSynchronization . By default the synchronization is set to
AUTO and the current DistributionStrategy chooses when to
synchronize.
|
aggregation
|
Indicates how a distributed variable will be aggregated.
Accepted values are constants defined in the class
tf.VariableAggregation .
|
shape
|
(optional) The shape of this variable. If None, the shape of
initial_value will be used. When setting this argument to
tf.TensorShape(None) (representing an unspecified shape), the variable
can be assigned with values of different shapes.
|
Raises | |
---|---|
ValueError
|
If both variable_def and initial_value are specified.
|
ValueError
|
If the initial value is not specified, or does not have a
shape and validate_shape is True .
|
RuntimeError
|
If eager execution is enabled. |
Attributes | |
---|---|
aggregation
|
|
constraint
|
Returns the constraint function associated with this variable. |
device
|
The device of this variable. |
dtype
|
The DType of this variable.
|
graph
|
The Graph of this variable.
|
initial_value
|
Returns the Tensor used as the initial value for the variable.
Note that this is different from |
initializer
|
The initializer operation for this variable. |
name
|
The name of this variable. |
op
|
The Operation of this variable.
|
shape
|
The TensorShape of this variable.
|
synchronization
|
|
trainable
|
Child Classes
Methods
assign
assign(
value, use_locking=False, name=None, read_value=True
)
Assigns a new value to the variable.
This is essentially a shortcut for assign(self, value)
.
Args | |
---|---|
value
|
A Tensor . The new value for this variable.
|
use_locking
|
If True , use locking during the assignment.
|
name
|
The name of the operation to be created |
read_value
|
if True, will return something which evaluates to the new value of the variable; if False will return the assign op. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the assignment has completed.
|
assign_add
assign_add(
delta, use_locking=False, name=None, read_value=True
)
Adds a value to this variable.
This is essentially a shortcut for assign_add(self, delta)
.
Args | |
---|---|
delta
|
A Tensor . The value to add to this variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
The name of the operation to be created |
read_value
|
if True, will return something which evaluates to the new value of the variable; if False will return the assign op. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the addition has completed.
|
assign_sub
assign_sub(
delta, use_locking=False, name=None, read_value=True
)
Subtracts a value from this variable.
This is essentially a shortcut for assign_sub(self, delta)
.
Args | |
---|---|
delta
|
A Tensor . The value to subtract from this variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
The name of the operation to be created |
read_value
|
if True, will return something which evaluates to the new value of the variable; if False will return the assign op. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the subtraction has completed.
|
batch_scatter_update
batch_scatter_update(
sparse_delta, use_locking=False, name=None
)
Assigns tf.IndexedSlices
to this variable batch-wise.
Analogous to batch_gather
. This assumes that this variable and the
sparse_delta IndexedSlices have a series of leading dimensions that are the
same for all of them, and the updates are performed on the last dimension of
indices. In other words, the dimensions should be the following:
num_prefix_dims = sparse_delta.indices.ndims - 1
batch_dim = num_prefix_dims + 1
sparse_delta.updates.shape = sparse_delta.indices.shape + var.shape[
batch_dim:]
where
sparse_delta.updates.shape[:num_prefix_dims]
== sparse_delta.indices.shape[:num_prefix_dims]
== var.shape[:num_prefix_dims]
And the operation performed can be expressed as:
var[i_1, ..., i_n,
sparse_delta.indices[i_1, ..., i_n, j]] = sparse_delta.updates[
i_1, ..., i_n, j]
When sparse_delta.indices is a 1D tensor, this operation is equivalent to
scatter_update
.
To avoid this operation one can looping over the first ndims
of the
variable and using scatter_update
on the subtensors that result of slicing
the first dimension. This is a valid option for ndims = 1
, but less
efficient than this implementation.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to be assigned to this variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered assignment has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
count_up_to
count_up_to(
limit
)
Increments this variable until it reaches limit
. (deprecated)
When that Op is run it tries to increment the variable by 1
. If
incrementing the variable would bring it above limit
then the Op raises
the exception OutOfRangeError
.
If no error is raised, the Op outputs the value of the variable before the increment.
This is essentially a shortcut for count_up_to(self, limit)
.
Args | |
---|---|
limit
|
value at which incrementing the variable raises an error. |
Returns | |
---|---|
A Tensor that will hold the variable value before the increment. If no
other Op modifies this variable, the values produced will all be
distinct.
|
eval
eval(
session=None
)
In a session, computes and returns the value of this variable.
This is not a graph construction method, it does not add ops to the graph.
This convenience method requires a session where the graph
containing this variable has been launched. If no session is
passed, the default session is used. See tf.compat.v1.Session
for more
information on launching a graph and on sessions.
v = tf.Variable([1, 2])
init = tf.compat.v1.global_variables_initializer()
with tf.compat.v1.Session() as sess:
sess.run(init)
# Usage passing the session explicitly.
print(v.eval(sess))
# Usage with the default session. The 'with' block
# above makes 'sess' the default session.
print(v.eval())
Args | |
---|---|
session
|
The session to use to evaluate this variable. If none, the default session is used. |
Returns | |
---|---|
A numpy ndarray with a copy of the value of this variable.
|
experimental_ref
experimental_ref()
Returns a hashable reference object to this Variable.
The primary usecase for this API is to put variables in a set/dictionary.
We can't put variables in a set/dictionary as variable.__hash__()
is no
longer available starting Tensorflow 2.0.
import tensorflow as tf
x = tf.Variable(5)
y = tf.Variable(10)
z = tf.Variable(10)
# The followings will raise an exception starting 2.0
# TypeError: Variable is unhashable if Variable equality is enabled.
variable_set = {x, y, z}
variable_dict = {x: 'five', y: 'ten'}
Instead, we can use variable.experimental_ref()
.
variable_set = {x.experimental_ref(),
y.experimental_ref(),
z.experimental_ref()}
print(x.experimental_ref() in variable_set)
==> True
variable_dict = {x.experimental_ref(): 'five',
y.experimental_ref(): 'ten',
z.experimental_ref(): 'ten'}
print(variable_dict[y.experimental_ref()])
==> ten
Also, the reference object provides .deref()
function that returns the
original Variable.
x = tf.Variable(5)
print(x.experimental_ref().deref())
==> <tf.Variable 'Variable:0' shape=() dtype=int32, numpy=5>
from_proto
@staticmethod
from_proto( variable_def, import_scope=None )
Returns a Variable
object created from variable_def
.
gather_nd
gather_nd(
indices, name=None
)
Gather slices from params
into a Tensor with shape specified by indices
.
See tf.gather_nd for details.
Args | |
---|---|
indices
|
A Tensor . Must be one of the following types: int32 , int64 .
Index tensor.
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor . Has the same type as params .
|
get_shape
get_shape()
Alias of Variable.shape
.
initialized_value
initialized_value()
Returns the value of the initialized variable. (deprecated)
You should use this instead of the variable itself to initialize another variable with a value that depends on the value of this variable.
# Initialize 'v' with a random tensor.
v = tf.Variable(tf.random.truncated_normal([10, 40]))
# Use `initialized_value` to guarantee that `v` has been
# initialized before its value is used to initialize `w`.
# The random values are picked only once.
w = tf.Variable(v.initialized_value() * 2.0)
Returns | |
---|---|
A Tensor holding the value of this variable after its initializer
has run.
|
load
load(
value, session=None
)
Load new value into this variable. (deprecated)
Writes new value to variable's memory. Doesn't add ops to the graph.
This convenience method requires a session where the graph
containing this variable has been launched. If no session is
passed, the default session is used. See tf.compat.v1.Session
for more
information on launching a graph and on sessions.
v = tf.Variable([1, 2])
init = tf.compat.v1.global_variables_initializer()
with tf.compat.v1.Session() as sess:
sess.run(init)
# Usage passing the session explicitly.
v.load([2, 3], sess)
print(v.eval(sess)) # prints [2 3]
# Usage with the default session. The 'with' block
# above makes 'sess' the default session.
v.load([3, 4], sess)
print(v.eval()) # prints [3 4]
Args | |
---|---|
value
|
New variable value |
session
|
The session to use to evaluate this variable. If none, the default session is used. |
Raises | |
---|---|
ValueError
|
Session is not passed and no default session |
read_value
read_value()
Returns the value of this variable, read in the current context.
Can be different from value() if it's on another device, with control dependencies, etc.
Returns | |
---|---|
A Tensor containing the value of the variable.
|
scatter_add
scatter_add(
sparse_delta, use_locking=False, name=None
)
Adds tf.IndexedSlices
to this variable.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to be added to this variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered addition has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
scatter_div
scatter_div(
sparse_delta, use_locking=False, name=None
)
Divide this variable by tf.IndexedSlices
.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to divide this variable by.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered division has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
scatter_max
scatter_max(
sparse_delta, use_locking=False, name=None
)
Updates this variable with the max of tf.IndexedSlices
and itself.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to use as an argument of max with this
variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered maximization has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
scatter_min
scatter_min(
sparse_delta, use_locking=False, name=None
)
Updates this variable with the min of tf.IndexedSlices
and itself.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to use as an argument of min with this
variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered minimization has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
scatter_mul
scatter_mul(
sparse_delta, use_locking=False, name=None
)
Multiply this variable by tf.IndexedSlices
.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to multiply this variable by.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered multiplication has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
scatter_nd_add
scatter_nd_add(
indices, updates, name=None
)
Applies sparse addition to individual values or slices in a Variable.
The Variable has rank P
and indices
is a Tensor
of rank Q
.
indices
must be integer tensor, containing indices into self.
It must be shape [d_0, ..., d_{Q-2}, K]
where 0 < K <= P
.
The innermost dimension of indices
(with length K
) corresponds to
indices into elements (if K = P
) or slices (if K < P
) along the K
th
dimension of self.
updates
is Tensor
of rank Q-1+P-K
with shape:
[d_0, ..., d_{Q-2}, self.shape[K], ..., self.shape[P-1]].
For example, say we want to add 4 scattered elements to a rank-1 tensor to 8 elements. In Python, that update would look like this:
v = tf.Variable([1, 2, 3, 4, 5, 6, 7, 8])
indices = tf.constant([[4], [3], [1] ,[7]])
updates = tf.constant([9, 10, 11, 12])
add = v.scatter_nd_add(indices, updates)
with tf.compat.v1.Session() as sess:
print sess.run(add)
The resulting update to v would look like this:
[1, 13, 3, 14, 14, 6, 7, 20]
See tf.scatter_nd
for more details about how to make updates to
slices.
Args | |
---|---|
indices
|
The indices to be used in the operation. |
updates
|
The values to be used in the operation. |
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered addition has completed.
|
scatter_nd_sub
scatter_nd_sub(
indices, updates, name=None
)
Applies sparse subtraction to individual values or slices in a Variable.
Assuming the variable has rank P
and indices
is a Tensor
of rank Q
.
indices
must be integer tensor, containing indices into self.
It must be shape [d_0, ..., d_{Q-2}, K]
where 0 < K <= P
.
The innermost dimension of indices
(with length K
) corresponds to
indices into elements (if K = P
) or slices (if K < P
) along the K
th
dimension of self.
updates
is Tensor
of rank Q-1+P-K
with shape:
[d_0, ..., d_{Q-2}, self.shape[K], ..., self.shape[P-1]].
For example, say we want to add 4 scattered elements to a rank-1 tensor to 8 elements. In Python, that update would look like this:
v = tf.Variable([1, 2, 3, 4, 5, 6, 7, 8])
indices = tf.constant([[4], [3], [1] ,[7]])
updates = tf.constant([9, 10, 11, 12])
op = v.scatter_nd_sub(indices, updates)
with tf.compat.v1.Session() as sess:
print sess.run(op)
The resulting update to v would look like this:
[1, -9, 3, -6, -6, 6, 7, -4]
See tf.scatter_nd
for more details about how to make updates to
slices.
Args | |
---|---|
indices
|
The indices to be used in the operation. |
updates
|
The values to be used in the operation. |
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered subtraction has completed.
|
scatter_nd_update
scatter_nd_update(
indices, updates, name=None
)
Applies sparse assignment to individual values or slices in a Variable.
The Variable has rank P
and indices
is a Tensor
of rank Q
.
indices
must be integer tensor, containing indices into self.
It must be shape [d_0, ..., d_{Q-2}, K]
where 0 < K <= P
.
The innermost dimension of indices
(with length K
) corresponds to
indices into elements (if K = P
) or slices (if K < P
) along the K
th
dimension of self.
updates
is Tensor
of rank Q-1+P-K
with shape:
[d_0, ..., d_{Q-2}, self.shape[K], ..., self.shape[P-1]].
For example, say we want to add 4 scattered elements to a rank-1 tensor to 8 elements. In Python, that update would look like this:
v = tf.Variable([1, 2, 3, 4, 5, 6, 7, 8])
indices = tf.constant([[4], [3], [1] ,[7]])
updates = tf.constant([9, 10, 11, 12])
op = v.scatter_nd_assign(indices, updates)
with tf.compat.v1.Session() as sess:
print sess.run(op)
The resulting update to v would look like this:
[1, 11, 3, 10, 9, 6, 7, 12]
See tf.scatter_nd
for more details about how to make updates to
slices.
Args | |
---|---|
indices
|
The indices to be used in the operation. |
updates
|
The values to be used in the operation. |
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered assignment has completed.
|
scatter_sub
scatter_sub(
sparse_delta, use_locking=False, name=None
)
Subtracts tf.IndexedSlices
from this variable.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to be subtracted from this variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered subtraction has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
scatter_update
scatter_update(
sparse_delta, use_locking=False, name=None
)
Assigns tf.IndexedSlices
to this variable.
Args | |
---|---|
sparse_delta
|
tf.IndexedSlices to be assigned to this variable.
|
use_locking
|
If True , use locking during the operation.
|
name
|
the name of the operation. |
Returns | |
---|---|
A Tensor that will hold the new value of this variable after
the scattered assignment has completed.
|
Raises | |
---|---|
TypeError
|
if sparse_delta is not an IndexedSlices .
|
set_shape
set_shape(
shape
)
Overrides the shape for this variable.
Args | |
---|---|
shape
|
the TensorShape representing the overridden shape.
|
sparse_read
sparse_read(
indices, name=None
)
Gather slices from params axis axis according to indices.
This function supports a subset of tf.gather, see tf.gather for details on usage.
Args | |
---|---|
indices
|
The index Tensor . Must be one of the following types: int32 ,
int64 . Must be in range [0, params.shape[axis]) .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor . Has the same type as params .
|
to_proto
to_proto(
export_scope=None
)
Converts a Variable
to a VariableDef
protocol buffer.
Args | |
---|---|
export_scope
|
Optional string . Name scope to remove.
|
Returns | |
---|---|
A VariableDef protocol buffer, or None if the Variable is not
in the specified name scope.
|
value
value()
Returns the last snapshot of this variable.
You usually do not need to call this method as all ops that need the value
of the variable call it automatically through a convert_to_tensor()
call.
Returns a Tensor
which holds the value of the variable. You can not
assign a new value to this tensor as it is not a reference to the variable.
To avoid copies, if the consumer of the returned value is on the same device as the variable, this actually returns the live value of the variable, not a copy. Updates to the variable are seen by the consumer. If the consumer is on a different device it will get a copy of the variable.
Returns | |
---|---|
A Tensor containing the value of the variable.
|
__abs__
__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 \(a + bj\). The
absolute value is computed as \( \sqrt{a^2 + b^2}\). For example:
x = tf.constant([[-2.25 + 4.75j], [-3.25 + 5.75j]])
tf.abs(x) # [5.25594902, 6.60492229]
Args | |
---|---|
x
|
A Tensor or SparseTensor of type float16 , float32 , float64 ,
int32 , int64 , complex64 or complex128 .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor or SparseTensor the same size, type, and sparsity as x with
absolute values.
Note, for complex64 or complex128 input, the returned Tensor will be
of type float32 or float64 , respectively.
|
__add__
__add__(
x, y
)
Dispatches to add for strings and add_v2 for all other types.
__and__
__and__(
x, y
)
Returns the truth value of x AND y element-wise.
Args | |
---|---|
x
|
A Tensor of type bool .
|
y
|
A Tensor of type bool .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__div__
__div__(
x, y
)
Divide two values using Python 2 semantics.
Used for Tensor.div.
Args | |
---|---|
x
|
Tensor numerator of real numeric type.
|
y
|
Tensor denominator of real numeric type.
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
x / y returns the quotient of x and y.
|
__eq__
__eq__(
other
)
Compares two variables element-wise for equality.
__floordiv__
__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
|
Tensor numerator of real numeric type.
|
y
|
Tensor denominator of real numeric type.
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
x / y rounded down.
|
Raises | |
---|---|
TypeError
|
If the inputs are complex. |
__ge__
__ge__(
x, y, name=None
)
Returns the truth value of (x >= y) element-wise.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: float32 , float64 , int32 , uint8 , int16 , int8 , int64 , bfloat16 , uint16 , half , uint32 , uint64 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__getitem__
__getitem__(
var, slice_spec
)
Creates a slice helper object given a variable.
This allows creating a sub-tensor from part of the current contents
of a variable. See tf.Tensor.getitem
for detailed examples
of slicing.
This function in addition also allows assignment to a sliced range.
This is similar to __setitem__
functionality in Python. However,
the syntax is different so that the user can capture the assignment
operation for grouping or passing to sess.run()
.
For example,
import tensorflow as tf
A = tf.Variable([[1,2,3], [4,5,6], [7,8,9]], dtype=tf.float32)
with tf.compat.v1.Session() as sess:
sess.run(tf.compat.v1.global_variables_initializer())
print(sess.run(A[:2, :2])) # => [[1,2], [4,5]]
op = A[:2,:2].assign(22. * tf.ones((2, 2)))
print(sess.run(op)) # => [[22, 22, 3], [22, 22, 6], [7,8,9]]
Note that assignments currently do not support NumPy broadcasting semantics.
Args | |
---|---|
var
|
An ops.Variable object.
|
slice_spec
|
The arguments to Tensor.getitem .
|
Returns | |
---|---|
The appropriate slice of "tensor", based on "slice_spec".
As an operator. The operator also has a assign() method
that can be used to generate an assignment operator.
|
Raises | |
---|---|
ValueError
|
If a slice range is negative size. |
TypeError
|
TypeError: If the slice indices aren't int, slice, ellipsis, tf.newaxis or int32/int64 tensors. |
__gt__
__gt__(
x, y, name=None
)
Returns the truth value of (x > y) element-wise.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: float32 , float64 , int32 , uint8 , int16 , int8 , int64 , bfloat16 , uint16 , half , uint32 , uint64 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__invert__
__invert__(
x, name=None
)
Returns the truth value of NOT x element-wise.
Args | |
---|---|
x
|
A Tensor of type bool .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__iter__
__iter__()
Dummy method to prevent iteration.
Do not call.
NOTE(mrry): If we register getitem as an overloaded operator, Python will valiantly attempt to iterate over the variable's Tensor from 0 to infinity. Declaring this method prevents this unintended behavior.
Raises | |
---|---|
TypeError
|
when invoked. |
__le__
__le__(
x, y, name=None
)
Returns the truth value of (x <= y) element-wise.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: float32 , float64 , int32 , uint8 , int16 , int8 , int64 , bfloat16 , uint16 , half , uint32 , uint64 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__lt__
__lt__(
x, y, name=None
)
Returns the truth value of (x < y) element-wise.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: float32 , float64 , int32 , uint8 , int16 , int8 , int64 , bfloat16 , uint16 , half , uint32 , uint64 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__matmul__
__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:
# 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
|
Tensor of type float16 , float32 , float64 , int32 , complex64 ,
complex128 and rank > 1.
|
b
|
Tensor with same type and rank as a .
|
transpose_a
|
If True , a is transposed before multiplication.
|
transpose_b
|
If True , b is transposed before multiplication.
|
adjoint_a
|
If True , a is conjugated and transposed before
multiplication.
|
adjoint_b
|
If True , b is conjugated and transposed before
multiplication.
|
a_is_sparse
|
If True , a is treated as a sparse matrix.
|
b_is_sparse
|
If True , b is treated as a sparse matrix.
|
name
|
Name for the operation (optional). |
Returns | |
---|---|
A Tensor of the same type as a and b where each inner-most matrix is
the product of the corresponding matrices in a and b , e.g. if all
transpose or adjoint attributes are False :
|
|
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. |
__mod__
__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
.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: int32 , int64 , bfloat16 , half , float32 , float64 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor . Has the same type as x .
|
__mul__
__mul__(
x, y
)
Dispatches cwise mul for "DenseDense" and "DenseSparse".
__ne__
__ne__(
other
)
Compares two variables element-wise for equality.
__neg__
__neg__(
x, name=None
)
Computes numerical negative value element-wise.
I.e., \(y = -x\).
Args | |
---|---|
x
|
A Tensor . 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 as x .
|
__or__
__or__(
x, y
)
Returns the truth value of x OR y element-wise.
Args | |
---|---|
x
|
A Tensor of type bool .
|
y
|
A Tensor of type bool .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__pow__
__pow__(
x, y
)
Computes the power of one value to another.
Given a tensor x
and a tensor y
, this operation computes \(x^y\) 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
|
A Tensor of type float16 , float32 , float64 , int32 , int64 ,
complex64 , or complex128 .
|
y
|
A Tensor of type float16 , float32 , float64 , int32 , int64 ,
complex64 , or complex128 .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor .
|
__radd__
__radd__(
y, x
)
Dispatches to add for strings and add_v2 for all other types.
__rand__
__rand__(
y, x
)
Returns the truth value of x AND y element-wise.
Args | |
---|---|
x
|
A Tensor of type bool .
|
y
|
A Tensor of type bool .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__rdiv__
__rdiv__(
y, x
)
Divide two values using Python 2 semantics.
Used for Tensor.div.
Args | |
---|---|
x
|
Tensor numerator of real numeric type.
|
y
|
Tensor denominator of real numeric type.
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
x / y returns the quotient of x and y.
|
__rfloordiv__
__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
|
Tensor numerator of real numeric type.
|
y
|
Tensor denominator of real numeric type.
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
x / y rounded down.
|
Raises | |
---|---|
TypeError
|
If the inputs are complex. |
__rmatmul__
__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:
# 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
|
Tensor of type float16 , float32 , float64 , int32 , complex64 ,
complex128 and rank > 1.
|
b
|
Tensor with same type and rank as a .
|
transpose_a
|
If True , a is transposed before multiplication.
|
transpose_b
|
If True , b is transposed before multiplication.
|
adjoint_a
|
If True , a is conjugated and transposed before
multiplication.
|
adjoint_b
|
If True , b is conjugated and transposed before
multiplication.
|
a_is_sparse
|
If True , a is treated as a sparse matrix.
|
b_is_sparse
|
If True , b is treated as a sparse matrix.
|
name
|
Name for the operation (optional). |
Returns | |
---|---|
A Tensor of the same type as a and b where each inner-most matrix is
the product of the corresponding matrices in a and b , e.g. if all
transpose or adjoint attributes are False :
|
|
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. |
__rmod__
__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
.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: int32 , int64 , bfloat16 , half , float32 , float64 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor . Has the same type as x .
|
__rmul__
__rmul__(
y, x
)
Dispatches cwise mul for "DenseDense" and "DenseSparse".
__ror__
__ror__(
y, x
)
Returns the truth value of x OR y element-wise.
Args | |
---|---|
x
|
A Tensor of type bool .
|
y
|
A Tensor of type bool .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor of type bool .
|
__rpow__
__rpow__(
y, x
)
Computes the power of one value to another.
Given a tensor x
and a tensor y
, this operation computes \(x^y\) 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
|
A Tensor of type float16 , float32 , float64 , int32 , int64 ,
complex64 , or complex128 .
|
y
|
A Tensor of type float16 , float32 , float64 , int32 , int64 ,
complex64 , or complex128 .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor .
|
__rsub__
__rsub__(
y, x
)
Returns x - y element-wise.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: bfloat16 , half , float32 , float64 , uint8 , int8 , uint16 , int16 , int32 , int64 , complex64 , complex128 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor . Has the same type as x .
|
__rtruediv__
__rtruediv__(
y, x
)
__rxor__
__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:
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
|
A Tensor type bool.
|
y
|
A Tensor of type bool.
|
Returns | |
---|---|
A Tensor of type bool with the same size as that of x or y.
|
__sub__
__sub__(
x, y
)
Returns x - y element-wise.
Args | |
---|---|
x
|
A Tensor . Must be one of the following types: bfloat16 , half , float32 , float64 , uint8 , int8 , uint16 , int16 , int32 , int64 , complex64 , complex128 .
|
y
|
A Tensor . Must have the same type as x .
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A Tensor . Has the same type as x .
|
__truediv__
__truediv__(
x, y
)
__xor__
__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:
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
|
A Tensor type bool.
|
y
|
A Tensor of type bool.
|
Returns | |
---|---|
A Tensor of type bool with the same size as that of x or y.
|