Package mdp :: Package nodes :: Class TimeDelayNode
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Class TimeDelayNode


Copy delayed version of the input signal on the space dimensions.

For example, for time_frames=3 and gap=2:

[ X(1) Y(1)        [ X(1) Y(1)   0    0    0    0
  X(2) Y(2)          X(2) Y(2)   0    0    0    0
  X(3) Y(3)   -->    X(3) Y(3) X(1) Y(1)   0    0
  X(4) Y(4)          X(4) Y(4) X(2) Y(2)   0    0
  X(5) Y(5)          X(5) Y(5) X(3) Y(3) X(1) Y(1)
  X(6) Y(6)          ...  ...  ...  ...  ...  ... ]
  X(7) Y(7)
  X(8) Y(8)
  ...  ...  ]

This node provides similar functionality as the TimeFramesNode, only that it performs a time embedding into the past rather than into the future.

See TimeDelaySlidingWindowNode for a sliding window delay node for application in a non-batch manner.

Original code contributed by Sebastian Hoefer. Dec 31, 2010

Instance Methods [hide private]
 
__init__(self, time_frames, gap=1, input_dim=None, dtype=None)
Initializes an object of type 'TimeDelayNode'.
 
_execute(self, x)
 
execute(self, x)
Process the data contained in x.
numpy.ndarray
pseudo_inverse(self, y)
This function returns a pseudo-inverse of the execute frame.

Inherited from unreachable.newobject: __long__, __native__, __nonzero__, __unicode__, next

Inherited from object: __delattr__, __format__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __setattr__, __sizeof__, __subclasshook__

    Inherited from TimeFramesNode
list
_get_supported_dtypes(self)
Return the data types supported by this node.
 
_set_input_dim(self, n)
 
_set_output_dim(self, n)
    Inherited from Node
 
__add__(self, other)
 
__call__(self, x, *args, **kwargs)
Calling an instance of Node is equivalent to calling its execute method.
 
__repr__(self)
repr(x)
 
__str__(self)
str(x)
 
_check_input(self, x)
 
_check_output(self, y)
 
_check_train_args(self, x, *args, **kwargs)
 
_get_train_seq(self)
 
_if_training_stop_training(self)
 
_inverse(self, x)
 
_pre_execution_checks(self, x)
This method contains all pre-execution checks.
 
_pre_inversion_checks(self, y)
This method contains all pre-inversion checks.
 
_refcast(self, x)
Helper function to cast arrays to the internal dtype.
 
_set_dtype(self, t)
 
_stop_training(self, *args, **kwargs)
 
_train(self, x)
 
copy(self, protocol=None)
Return a deep copy of the node.
 
get_current_train_phase(self)
Return the index of the current training phase.
 
get_dtype(self)
Return dtype.
 
get_input_dim(self)
Return input dimensions.
 
get_output_dim(self)
Return output dimensions.
 
get_remaining_train_phase(self)
Return the number of training phases still to accomplish.
 
get_supported_dtypes(self)
Return dtypes supported by the node as a list of numpy.dtype objects.
 
has_multiple_training_phases(self)
Return True if the node has multiple training phases.
 
inverse(self, y, *args, **kwargs)
Invert y.
 
is_training(self)
Return True if the node is in the training phase, False otherwise.
 
save(self, filename, protocol=-1)
Save a pickled serialization of the node to filename. If filename is None, return a string.
 
set_dtype(self, t)
Set internal structures' dtype.
 
set_input_dim(self, n)
Set input dimensions.
 
set_output_dim(self, n)
Set output dimensions.
 
stop_training(self, *args, **kwargs)
Stop the training phase.
 
train(self, x, *args, **kwargs)
Update the internal structures according to the input data x.
Static Methods [hide private]
    Inherited from TimeFramesNode
 
is_invertible()
Return True if the node can be inverted, False otherwise.
 
is_trainable()
Return True if the node can be trained, False otherwise.
Properties [hide private]

Inherited from object: __class__

    Inherited from Node
  _train_seq
List of tuples:
  dtype
dtype
  input_dim
Input dimensions
  output_dim
Output dimensions
  supported_dtypes
Supported dtypes
Method Details [hide private]

__init__(self, time_frames, gap=1, input_dim=None, dtype=None)
(Constructor)

 
Initializes an object of type 'TimeDelayNode'.
Parameters:
  • time_frames (int) - Number of delayed copies.
  • gap (int) - Time delay between the copies.
  • input_dim (int) - The input dimensionality.
  • dtype (numpy.dtype) - The datatype.
Overrides: object.__init__

_execute(self, x)

 
Overrides: Node._execute

execute(self, x)

 

Process the data contained in x.

If the object is still in the training phase, the function stop_training will be called. x is a matrix having different variables on different columns and observations on the rows.

By default, subclasses should overwrite _execute to implement their execution phase. The docstring of the _execute method overwrites this docstring.

Overrides: Node.execute

pseudo_inverse(self, y)

 

This function returns a pseudo-inverse of the execute frame.

y == execute(x) is only True if y belongs to the domain of execute and has been computed with a sufficently large x. If gap > 1 some of the last rows will be filled with zeros.

Parameters:
  • y - The execute frame.
Returns: numpy.ndarray
A pseudo-inverse of the given frame.
Raises:
  • mdp.NodeException - When called. This method overrides the corresponding method of the ``TimeFramesNode*.
Overrides: TimeFramesNode.pseudo_inverse