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Layers

Various neural network layer types

Apply (Module)

A torch module for applying an arithmetic operator on an input tensor

Source code in evotorch/neuroevolution/net/layers.py 
class Apply(nn.Module):
    """A torch module for applying an arithmetic operator on an input tensor"""

    def __init__(self, operator: str, argument: float):
        """`__init__(...)`: Initialize the Apply module.

        Args:
            operator: Must be '+', '-', '*', '/', or '**'.
                Indicates which operation will be done
                on the input tensor.
            argument: Expected as a float, represents
                the right-argument of the operation
                (the left-argument being the input
                tensor).
        """
        nn.Module.__init__(self)

        self._operator = str(operator)
        assert self._operator in ("+", "-", "*", "/", "**")

        self._argument = float(argument)

    def forward(self, x):
        op = self._operator
        arg = self._argument
        if op == "+":
            return x + arg
        elif op == "-":
            return x - arg
        elif op == "*":
            return x * arg
        elif op == "/":
            return x / arg
        elif op == "**":
            return x**arg
        else:
            raise ValueError("Unknown operator:" + repr(op))

    def extra_repr(self):
        return "operator={}, argument={}".format(repr(self._operator), self._argument)

__init__(self, operator, argument) special

__init__(...): Initialize the Apply module.

Parameters:

Name Type Description Default
operator str

Must be '+', '-', '', '/', or '*'. Indicates which operation will be done on the input tensor.

 required
argument float

Expected as a float, represents the right-argument of the operation (the left-argument being the input tensor).

 required
Source code in evotorch/neuroevolution/net/layers.py 
def __init__(self, operator: str, argument: float):
    """`__init__(...)`: Initialize the Apply module.

    Args:
        operator: Must be '+', '-', '*', '/', or '**'.
            Indicates which operation will be done
            on the input tensor.
        argument: Expected as a float, represents
            the right-argument of the operation
            (the left-argument being the input
            tensor).
    """
    nn.Module.__init__(self)

    self._operator = str(operator)
    assert self._operator in ("+", "-", "*", "/", "**")

    self._argument = float(argument)

extra_repr(self)

Set the extra representation of the module

To print customized extra information, you should re-implement this method in your own modules. Both single-line and multi-line strings are acceptable.

Source code in evotorch/neuroevolution/net/layers.py 
def extra_repr(self):
    return "operator={}, argument={}".format(repr(self._operator), self._argument)

forward(self, x)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x):
    op = self._operator
    arg = self._argument
    if op == "+":
        return x + arg
    elif op == "-":
        return x - arg
    elif op == "*":
        return x * arg
    elif op == "/":
        return x / arg
    elif op == "**":
        return x**arg
    else:
        raise ValueError("Unknown operator:" + repr(op))

Bin (Module)

A small torch module for binning the values of tensors.

In more details, considering a lower bound value lb, an upper bound value ub, and an input tensor x, each value within x closer to lb will be converted to lb and each value within x closer to ub will be converted to ub.

Source code in evotorch/neuroevolution/net/layers.py 
class Bin(nn.Module):
    """A small torch module for binning the values of tensors.

    In more details, considering a lower bound value lb,
    an upper bound value ub, and an input tensor x,
    each value within x closer to lb will be converted to lb
    and each value within x closer to ub will be converted to ub.
    """

    def __init__(self, lb: float, ub: float):
        """`__init__(...)`: Initialize the Clip operator.

        Args:
            lb: Lower bound
            ub: Upper bound
        """
        nn.Module.__init__(self)
        self._lb = float(lb)
        self._ub = float(ub)
        self._interval_size = self._ub - self._lb
        self._shrink_amount = self._interval_size / 2.0
        self._shift_amount = (self._ub + self._lb) / 2.0

    def forward(self, x: torch.Tensor):
        x = x - self._shift_amount
        x = x / self._shrink_amount
        x = torch.sign(x)
        x = x * self._shrink_amount
        x = x + self._shift_amount
        return x

    def extra_repr(self):
        return "lb={}, ub={}".format(self._lb, self._ub)

__init__(self, lb, ub) special

__init__(...): Initialize the Clip operator.

Parameters:

Name Type Description Default
lb float

Lower bound

 required
ub float

Upper bound

 required
Source code in evotorch/neuroevolution/net/layers.py 
def __init__(self, lb: float, ub: float):
    """`__init__(...)`: Initialize the Clip operator.

    Args:
        lb: Lower bound
        ub: Upper bound
    """
    nn.Module.__init__(self)
    self._lb = float(lb)
    self._ub = float(ub)
    self._interval_size = self._ub - self._lb
    self._shrink_amount = self._interval_size / 2.0
    self._shift_amount = (self._ub + self._lb) / 2.0

extra_repr(self)

Set the extra representation of the module

To print customized extra information, you should re-implement this method in your own modules. Both single-line and multi-line strings are acceptable.

Source code in evotorch/neuroevolution/net/layers.py 
def extra_repr(self):
    return "lb={}, ub={}".format(self._lb, self._ub)

forward(self, x)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor):
    x = x - self._shift_amount
    x = x / self._shrink_amount
    x = torch.sign(x)
    x = x * self._shrink_amount
    x = x + self._shift_amount
    return x

Clip (Module)

A small torch module for clipping the values of tensors

Source code in evotorch/neuroevolution/net/layers.py 
class Clip(nn.Module):
    """A small torch module for clipping the values of tensors"""

    def __init__(self, lb: float, ub: float):
        """`__init__(...)`: Initialize the Clip operator.

        Args:
            lb: Lower bound. Values less than this will be clipped.
            ub: Upper bound. Values greater than this will be clipped.
        """
        nn.Module.__init__(self)
        self._lb = float(lb)
        self._ub = float(ub)

    def forward(self, x: torch.Tensor):
        return x.clamp(self._lb, self._ub)

    def extra_repr(self):
        return "lb={}, ub={}".format(self._lb, self._ub)

__init__(self, lb, ub) special

__init__(...): Initialize the Clip operator.

Parameters:

Name Type Description Default
lb float

Lower bound. Values less than this will be clipped.

 required
ub float

Upper bound. Values greater than this will be clipped.

 required
Source code in evotorch/neuroevolution/net/layers.py 
def __init__(self, lb: float, ub: float):
    """`__init__(...)`: Initialize the Clip operator.

    Args:
        lb: Lower bound. Values less than this will be clipped.
        ub: Upper bound. Values greater than this will be clipped.
    """
    nn.Module.__init__(self)
    self._lb = float(lb)
    self._ub = float(ub)

extra_repr(self)

Set the extra representation of the module

To print customized extra information, you should re-implement this method in your own modules. Both single-line and multi-line strings are acceptable.

Source code in evotorch/neuroevolution/net/layers.py 
def extra_repr(self):
    return "lb={}, ub={}".format(self._lb, self._ub)

forward(self, x)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor):
    return x.clamp(self._lb, self._ub)

FeedForwardNet (Module)

Representation of a feed forward neural network as a torch Module.

An example initialization of a FeedForwardNet is as follows:

net = drt.FeedForwardNet(4, [(8, 'tanh'), (6, 'tanh')])

which means that we would like to have a network which expects an input vector of length 4 and passes its input through 2 tanh-activated hidden layers (with neurons count 8 and 6, respectively). The output of the last hidden layer (of length 6) is the final output vector.

The string representation of the module obtained via the example above is:

FeedForwardNet(
  (layer_0): Linear(in_features=4, out_features=8, bias=True)
  (actfunc_0): Tanh()
  (layer_1): Linear(in_features=8, out_features=6, bias=True)
  (actfunc_1): Tanh()
)
Source code in evotorch/neuroevolution/net/layers.py 
class FeedForwardNet(nn.Module):
    """
    Representation of a feed forward neural network as a torch Module.

    An example initialization of a FeedForwardNet is as follows:

        net = drt.FeedForwardNet(4, [(8, 'tanh'), (6, 'tanh')])

    which means that we would like to have a network which expects an input
    vector of length 4 and passes its input through 2 tanh-activated hidden
    layers (with neurons count 8 and 6, respectively).
    The output of the last hidden layer (of length 6) is the final
    output vector.

    The string representation of the module obtained via the example above
    is:

        FeedForwardNet(
          (layer_0): Linear(in_features=4, out_features=8, bias=True)
          (actfunc_0): Tanh()
          (layer_1): Linear(in_features=8, out_features=6, bias=True)
          (actfunc_1): Tanh()
        )
    """

    LengthActTuple = Tuple[int, Union[str, Callable]]
    LengthActBiasTuple = Tuple[int, Union[str, Callable], Union[bool]]

    def __init__(self, input_size: int, layers: List[Union[LengthActTuple, LengthActBiasTuple]]):
        """`__init__(...)`: Initialize the FeedForward network.

        Args:
            input_size: Input size of the network, expected as an int.
            layers: Expected as a list of tuples,
                where each tuple is either of the form
                `(layer_size, activation_function)`
                or of the form
                `(layer_size, activation_function, bias)`
                in which
                (i) `layer_size` is an int, specifying the number of neurons;
                (ii) `activation_function` is None, or a callable object,
                or a string containing the name of the activation function
                ('relu', 'selu', 'elu', 'tanh', 'hardtanh', or 'sigmoid');
                (iii) `bias` is a boolean, specifying whether the layer
                is to have a bias or not.
                When omitted, bias is set to True.
        """

        nn.Module.__init__(self)

        for i, layer in enumerate(layers):
            if len(layer) == 2:
                size, actfunc = layer
                bias = True
            elif len(layer) == 3:
                size, actfunc, bias = layer
            else:
                assert False, "A layer tuple of invalid size is encountered"

            setattr(self, "layer_" + str(i), nn.Linear(input_size, size, bias=bias))

            if isinstance(actfunc, str):
                if actfunc == "relu":
                    actfunc = nn.ReLU()
                elif actfunc == "selu":
                    actfunc = nn.SELU()
                elif actfunc == "elu":
                    actfunc = nn.ELU()
                elif actfunc == "tanh":
                    actfunc = nn.Tanh()
                elif actfunc == "hardtanh":
                    actfunc = nn.Hardtanh()
                elif actfunc == "sigmoid":
                    actfunc = nn.Sigmoid()
                elif actfunc == "round":
                    actfunc = Round()
                else:
                    raise ValueError("Unknown activation function: " + repr(actfunc))

            setattr(self, "actfunc_" + str(i), actfunc)

            input_size = size

    def forward(self, x):
        i = 0
        while hasattr(self, "layer_" + str(i)):
            x = getattr(self, "layer_" + str(i))(x)
            f = getattr(self, "actfunc_" + str(i))
            if f is not None:
                x = f(x)
            i += 1
        return x

__init__(self, input_size, layers) special

__init__(...): Initialize the FeedForward network.

Parameters:

Name Type Description Default
input_size int

Input size of the network, expected as an int.

 required
layers List[Union[Tuple[int, Union[str, Callable]], Tuple[int, Union[str, Callable], bool]]]

Expected as a list of tuples, where each tuple is either of the form (layer_size, activation_function) or of the form (layer_size, activation_function, bias) in which (i) layer_size is an int, specifying the number of neurons; (ii) activation_function is None, or a callable object, or a string containing the name of the activation function ('relu', 'selu', 'elu', 'tanh', 'hardtanh', or 'sigmoid'); (iii) bias is a boolean, specifying whether the layer is to have a bias or not. When omitted, bias is set to True.

 required
Source code in evotorch/neuroevolution/net/layers.py 
def __init__(self, input_size: int, layers: List[Union[LengthActTuple, LengthActBiasTuple]]):
    """`__init__(...)`: Initialize the FeedForward network.

    Args:
        input_size: Input size of the network, expected as an int.
        layers: Expected as a list of tuples,
            where each tuple is either of the form
            `(layer_size, activation_function)`
            or of the form
            `(layer_size, activation_function, bias)`
            in which
            (i) `layer_size` is an int, specifying the number of neurons;
            (ii) `activation_function` is None, or a callable object,
            or a string containing the name of the activation function
            ('relu', 'selu', 'elu', 'tanh', 'hardtanh', or 'sigmoid');
            (iii) `bias` is a boolean, specifying whether the layer
            is to have a bias or not.
            When omitted, bias is set to True.
    """

    nn.Module.__init__(self)

    for i, layer in enumerate(layers):
        if len(layer) == 2:
            size, actfunc = layer
            bias = True
        elif len(layer) == 3:
            size, actfunc, bias = layer
        else:
            assert False, "A layer tuple of invalid size is encountered"

        setattr(self, "layer_" + str(i), nn.Linear(input_size, size, bias=bias))

        if isinstance(actfunc, str):
            if actfunc == "relu":
                actfunc = nn.ReLU()
            elif actfunc == "selu":
                actfunc = nn.SELU()
            elif actfunc == "elu":
                actfunc = nn.ELU()
            elif actfunc == "tanh":
                actfunc = nn.Tanh()
            elif actfunc == "hardtanh":
                actfunc = nn.Hardtanh()
            elif actfunc == "sigmoid":
                actfunc = nn.Sigmoid()
            elif actfunc == "round":
                actfunc = Round()
            else:
                raise ValueError("Unknown activation function: " + repr(actfunc))

        setattr(self, "actfunc_" + str(i), actfunc)

        input_size = size

forward(self, x)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x):
    i = 0
    while hasattr(self, "layer_" + str(i)):
        x = getattr(self, "layer_" + str(i))(x)
        f = getattr(self, "actfunc_" + str(i))
        if f is not None:
            x = f(x)
        i += 1
    return x

LSTM (Module)

Source code in evotorch/neuroevolution/net/layers.py 
class LSTM(nn.Module):
    def __init__(
        self,
        input_size: int,
        hidden_size: int,
        *,
        dtype: torch.dtype = torch.float32,
        device: Union[str, torch.device] = "cpu",
    ):
        super().__init__()
        input_size = int(input_size)
        hidden_size = int(hidden_size)

        self.input_size = input_size
        self.hidden_size = hidden_size

        def input_weight():
            return nn.Parameter(torch.randn(self.hidden_size, self.input_size, dtype=dtype, device=device))

        def weight():
            return nn.Parameter(torch.randn(self.hidden_size, self.hidden_size, dtype=dtype, device=device))

        def bias():
            return nn.Parameter(torch.zeros(self.hidden_size, dtype=dtype, device=device))

        self.W_ii = input_weight()
        self.W_if = input_weight()
        self.W_ig = input_weight()
        self.W_io = input_weight()

        self.W_hi = weight()
        self.W_hf = weight()
        self.W_hg = weight()
        self.W_ho = weight()

        self.b_ii = bias()
        self.b_if = bias()
        self.b_ig = bias()
        self.b_io = bias()

        self.b_hi = bias()
        self.b_hf = bias()
        self.b_hg = bias()
        self.b_ho = bias()

    def forward(self, x: torch.Tensor, hidden=None) -> tuple:
        sigm = torch.sigmoid
        tanh = torch.tanh

        if hidden is None:
            h_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
            c_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
        else:
            h_prev, c_prev = hidden

        i_t = sigm(self.W_ii @ x + self.b_ii + self.W_hi @ h_prev + self.b_hi)
        f_t = sigm(self.W_if @ x + self.b_if + self.W_hf @ h_prev + self.b_hf)
        g_t = tanh(self.W_ig @ x + self.b_ig + self.W_hg @ h_prev + self.b_hg)
        o_t = sigm(self.W_io @ x + self.b_io + self.W_ho @ h_prev + self.b_ho)
        c_t = f_t * c_prev + i_t * g_t
        h_t = o_t * tanh(c_t)

        return h_t, (h_t, c_t)

    def __repr__(self) -> str:
        clsname = type(self).__name__
        return f"{clsname}(input_size={self.input_size}, hidden_size={self.hidden_size})"

forward(self, x, hidden=None)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor, hidden=None) -> tuple:
    sigm = torch.sigmoid
    tanh = torch.tanh

    if hidden is None:
        h_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
        c_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
    else:
        h_prev, c_prev = hidden

    i_t = sigm(self.W_ii @ x + self.b_ii + self.W_hi @ h_prev + self.b_hi)
    f_t = sigm(self.W_if @ x + self.b_if + self.W_hf @ h_prev + self.b_hf)
    g_t = tanh(self.W_ig @ x + self.b_ig + self.W_hg @ h_prev + self.b_hg)
    o_t = sigm(self.W_io @ x + self.b_io + self.W_ho @ h_prev + self.b_ho)
    c_t = f_t * c_prev + i_t * g_t
    h_t = o_t * tanh(c_t)

    return h_t, (h_t, c_t)

LSTMNet (Module)

Source code in evotorch/neuroevolution/net/layers.py 
class LSTM(nn.Module):
    def __init__(
        self,
        input_size: int,
        hidden_size: int,
        *,
        dtype: torch.dtype = torch.float32,
        device: Union[str, torch.device] = "cpu",
    ):
        super().__init__()
        input_size = int(input_size)
        hidden_size = int(hidden_size)

        self.input_size = input_size
        self.hidden_size = hidden_size

        def input_weight():
            return nn.Parameter(torch.randn(self.hidden_size, self.input_size, dtype=dtype, device=device))

        def weight():
            return nn.Parameter(torch.randn(self.hidden_size, self.hidden_size, dtype=dtype, device=device))

        def bias():
            return nn.Parameter(torch.zeros(self.hidden_size, dtype=dtype, device=device))

        self.W_ii = input_weight()
        self.W_if = input_weight()
        self.W_ig = input_weight()
        self.W_io = input_weight()

        self.W_hi = weight()
        self.W_hf = weight()
        self.W_hg = weight()
        self.W_ho = weight()

        self.b_ii = bias()
        self.b_if = bias()
        self.b_ig = bias()
        self.b_io = bias()

        self.b_hi = bias()
        self.b_hf = bias()
        self.b_hg = bias()
        self.b_ho = bias()

    def forward(self, x: torch.Tensor, hidden=None) -> tuple:
        sigm = torch.sigmoid
        tanh = torch.tanh

        if hidden is None:
            h_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
            c_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
        else:
            h_prev, c_prev = hidden

        i_t = sigm(self.W_ii @ x + self.b_ii + self.W_hi @ h_prev + self.b_hi)
        f_t = sigm(self.W_if @ x + self.b_if + self.W_hf @ h_prev + self.b_hf)
        g_t = tanh(self.W_ig @ x + self.b_ig + self.W_hg @ h_prev + self.b_hg)
        o_t = sigm(self.W_io @ x + self.b_io + self.W_ho @ h_prev + self.b_ho)
        c_t = f_t * c_prev + i_t * g_t
        h_t = o_t * tanh(c_t)

        return h_t, (h_t, c_t)

    def __repr__(self) -> str:
        clsname = type(self).__name__
        return f"{clsname}(input_size={self.input_size}, hidden_size={self.hidden_size})"

forward(self, x, hidden=None)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor, hidden=None) -> tuple:
    sigm = torch.sigmoid
    tanh = torch.tanh

    if hidden is None:
        h_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
        c_prev = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
    else:
        h_prev, c_prev = hidden

    i_t = sigm(self.W_ii @ x + self.b_ii + self.W_hi @ h_prev + self.b_hi)
    f_t = sigm(self.W_if @ x + self.b_if + self.W_hf @ h_prev + self.b_hf)
    g_t = tanh(self.W_ig @ x + self.b_ig + self.W_hg @ h_prev + self.b_hg)
    o_t = sigm(self.W_io @ x + self.b_io + self.W_ho @ h_prev + self.b_ho)
    c_t = f_t * c_prev + i_t * g_t
    h_t = o_t * tanh(c_t)

    return h_t, (h_t, c_t)

LocomotorNet (Module)

This is a control network which consists of two components: one linear, and one non-linear. The non-linear component is an input-independent set of sinusoidals waves whose amplitudes, frequencies and phases are trainable. Upon execution of a forward pass, the output of the non-linear component is the sum of all these sinusoidal waves. The linear component is a linear layer (optionally with bias) whose weights (and biases) are trainable. The final output of the LocomotorNet at the end of a forward pass is the sum of the linear and the non-linear components.

Note that this is a stateful network, where the only state is the timestep t, which starts from 0 and gets incremented by 1 at the end of each forward pass. The reset() method resets t back to 0.

Reference

Mario Srouji, Jian Zhang, Ruslan Salakhutdinov (2018). Structured Control Nets for Deep Reinforcement Learning.

Source code in evotorch/neuroevolution/net/layers.py 
class LocomotorNet(nn.Module):
    """LocomotorNet: A locomotion-specific structured control net.

    This is a control network which consists of two components:
    one linear, and one non-linear. The non-linear component
    is an input-independent set of sinusoidals waves whose
    amplitudes, frequencies and phases are trainable.
    Upon execution of a forward pass, the output of the non-linear
    component is the sum of all these sinusoidal waves.
    The linear component is a linear layer (optionally with bias)
    whose weights (and biases) are trainable.
    The final output of the LocomotorNet at the end of a forward pass
    is the sum of the linear and the non-linear components.

    Note that this is a stateful network, where the only state
    is the timestep t, which starts from 0 and gets incremented by 1
    at the end of each forward pass. The `reset()` method resets
    t back to 0.

    Reference:
        Mario Srouji, Jian Zhang, Ruslan Salakhutdinov (2018).
        Structured Control Nets for Deep Reinforcement Learning.
    """

    def __init__(self, *, in_features: int, out_features: int, bias: bool = True, num_sinusoids=16):
        """`__init__(...)`: Initialize the LocomotorNet.

        Args:
            in_features: Length of the input vector
            out_features: Length of the output vector
            bias: Whether or not the linear component is to have a bias
            num_sinusoids: Number of sinusoidal waves
        """

        nn.Module.__init__(self)

        self._in_features = in_features
        self._out_features = out_features
        self._bias = bias
        self._num_sinusoids = num_sinusoids

        self._linear_component = nn.Linear(
            in_features=self._in_features, out_features=self._out_features, bias=self._bias
        )

        self._amplitudes = nn.ParameterList()
        self._frequencies = nn.ParameterList()
        self._phases = nn.ParameterList()

        for _ in range(self._num_sinusoids):
            for paramlist in (self._amplitudes, self._frequencies, self._phases):
                paramlist.append(nn.Parameter(torch.randn(self._out_features, dtype=torch.float32)))

        self.reset()

    def reset(self):
        """Set the timestep t to 0"""
        self._t = 0

    @property
    def t(self) -> int:
        """The current timestep t"""
        return self._t

    @property
    def in_features(self) -> int:
        """Get the length of the input vector"""
        return self._in_features

    @property
    def out_features(self) -> int:
        """Get the length of the output vector"""
        return self._out_features

    @property
    def num_sinusoids(self) -> int:
        """Get the number of sinusoidal waves of the non-linear component"""
        return self._num_sinusoids

    @property
    def bias(self) -> bool:
        """Get whether or not the linear component has bias"""
        return self._bias

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        """Execute a forward pass"""
        u_linear = self._linear_component(x)

        t = self._t
        u_nonlinear = torch.zeros(self._out_features)
        for i in range(self._num_sinusoids):
            A = self._amplitudes[i]
            w = self._frequencies[i]
            phi = self._phases[i]
            u_nonlinear = u_nonlinear + (A * torch.sin(w * t + phi))

        self._t += 1

        return u_linear + u_nonlinear

bias: bool property readonly

Get whether or not the linear component has bias

in_features: int property readonly

Get the length of the input vector

num_sinusoids: int property readonly

Get the number of sinusoidal waves of the non-linear component

out_features: int property readonly

Get the length of the output vector

t: int property readonly

The current timestep t

__init__(self, *, in_features, out_features, bias=True, num_sinusoids=16) special

__init__(...): Initialize the LocomotorNet.

Parameters:

Name Type Description Default
in_features int

Length of the input vector

 required
out_features int

Length of the output vector

 required
bias bool

Whether or not the linear component is to have a bias

 True
num_sinusoids

Number of sinusoidal waves

 16
Source code in evotorch/neuroevolution/net/layers.py 
def __init__(self, *, in_features: int, out_features: int, bias: bool = True, num_sinusoids=16):
    """`__init__(...)`: Initialize the LocomotorNet.

    Args:
        in_features: Length of the input vector
        out_features: Length of the output vector
        bias: Whether or not the linear component is to have a bias
        num_sinusoids: Number of sinusoidal waves
    """

    nn.Module.__init__(self)

    self._in_features = in_features
    self._out_features = out_features
    self._bias = bias
    self._num_sinusoids = num_sinusoids

    self._linear_component = nn.Linear(
        in_features=self._in_features, out_features=self._out_features, bias=self._bias
    )

    self._amplitudes = nn.ParameterList()
    self._frequencies = nn.ParameterList()
    self._phases = nn.ParameterList()

    for _ in range(self._num_sinusoids):
        for paramlist in (self._amplitudes, self._frequencies, self._phases):
            paramlist.append(nn.Parameter(torch.randn(self._out_features, dtype=torch.float32)))

    self.reset()

forward(self, x)

Execute a forward pass

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor) -> torch.Tensor:
    """Execute a forward pass"""
    u_linear = self._linear_component(x)

    t = self._t
    u_nonlinear = torch.zeros(self._out_features)
    for i in range(self._num_sinusoids):
        A = self._amplitudes[i]
        w = self._frequencies[i]
        phi = self._phases[i]
        u_nonlinear = u_nonlinear + (A * torch.sin(w * t + phi))

    self._t += 1

    return u_linear + u_nonlinear

reset(self)

Set the timestep t to 0

Source code in evotorch/neuroevolution/net/layers.py 
def reset(self):
    """Set the timestep t to 0"""
    self._t = 0

RNN (Module)

Source code in evotorch/neuroevolution/net/layers.py 
class RNN(nn.Module):
    def __init__(
        self,
        input_size: int,
        hidden_size: int,
        nonlinearity: str = "tanh",
        *,
        dtype: torch.dtype = torch.float32,
        device: Union[str, torch.device] = "cpu",
    ):
        super().__init__()

        input_size = int(input_size)
        hidden_size = int(hidden_size)
        nonlinearity = str(nonlinearity)

        self.W1 = nn.Parameter(torch.randn(hidden_size, input_size, dtype=dtype, device=device))
        self.W2 = nn.Parameter(torch.randn(hidden_size, hidden_size, dtype=dtype, device=device))
        self.b1 = nn.Parameter(torch.zeros(hidden_size, dtype=dtype, device=device))
        self.b2 = nn.Parameter(torch.zeros(hidden_size, dtype=dtype, device=device))

        if nonlinearity == "tanh":
            self.actfunc = torch.tanh
        else:
            self.actfunc = getattr(nnf, nonlinearity)

        self.nonlinearity = nonlinearity
        self.input_size = input_size
        self.hidden_size = hidden_size

    def forward(self, x: torch.Tensor, h: Optional[torch.Tensor] = None) -> tuple:
        if h is None:
            h = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
        act = self.actfunc
        W1 = self.W1
        W2 = self.W2
        b1 = self.b1.unsqueeze(-1)
        b2 = self.b2.unsqueeze(-1)
        x = x.unsqueeze(-1)
        h = h.unsqueeze(-1)
        y = act(((W1 @ x) + b1) + ((W2 @ h) + b2))
        y = y.squeeze(-1)
        return y, y

    def __repr__(self) -> str:
        clsname = type(self).__name__
        return f"{clsname}(input_size={self.input_size}, hidden_size={self.hidden_size}, nonlinearity={repr(self.nonlinearity)})"

forward(self, x, h=None)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor, h: Optional[torch.Tensor] = None) -> tuple:
    if h is None:
        h = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
    act = self.actfunc
    W1 = self.W1
    W2 = self.W2
    b1 = self.b1.unsqueeze(-1)
    b2 = self.b2.unsqueeze(-1)
    x = x.unsqueeze(-1)
    h = h.unsqueeze(-1)
    y = act(((W1 @ x) + b1) + ((W2 @ h) + b2))
    y = y.squeeze(-1)
    return y, y

RecurrentNet (Module)

Source code in evotorch/neuroevolution/net/layers.py 
class RNN(nn.Module):
    def __init__(
        self,
        input_size: int,
        hidden_size: int,
        nonlinearity: str = "tanh",
        *,
        dtype: torch.dtype = torch.float32,
        device: Union[str, torch.device] = "cpu",
    ):
        super().__init__()

        input_size = int(input_size)
        hidden_size = int(hidden_size)
        nonlinearity = str(nonlinearity)

        self.W1 = nn.Parameter(torch.randn(hidden_size, input_size, dtype=dtype, device=device))
        self.W2 = nn.Parameter(torch.randn(hidden_size, hidden_size, dtype=dtype, device=device))
        self.b1 = nn.Parameter(torch.zeros(hidden_size, dtype=dtype, device=device))
        self.b2 = nn.Parameter(torch.zeros(hidden_size, dtype=dtype, device=device))

        if nonlinearity == "tanh":
            self.actfunc = torch.tanh
        else:
            self.actfunc = getattr(nnf, nonlinearity)

        self.nonlinearity = nonlinearity
        self.input_size = input_size
        self.hidden_size = hidden_size

    def forward(self, x: torch.Tensor, h: Optional[torch.Tensor] = None) -> tuple:
        if h is None:
            h = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
        act = self.actfunc
        W1 = self.W1
        W2 = self.W2
        b1 = self.b1.unsqueeze(-1)
        b2 = self.b2.unsqueeze(-1)
        x = x.unsqueeze(-1)
        h = h.unsqueeze(-1)
        y = act(((W1 @ x) + b1) + ((W2 @ h) + b2))
        y = y.squeeze(-1)
        return y, y

    def __repr__(self) -> str:
        clsname = type(self).__name__
        return f"{clsname}(input_size={self.input_size}, hidden_size={self.hidden_size}, nonlinearity={repr(self.nonlinearity)})"

forward(self, x, h=None)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor, h: Optional[torch.Tensor] = None) -> tuple:
    if h is None:
        h = torch.zeros(self.hidden_size, dtype=x.dtype, device=x.device)
    act = self.actfunc
    W1 = self.W1
    W2 = self.W2
    b1 = self.b1.unsqueeze(-1)
    b2 = self.b2.unsqueeze(-1)
    x = x.unsqueeze(-1)
    h = h.unsqueeze(-1)
    y = act(((W1 @ x) + b1) + ((W2 @ h) + b2))
    y = y.squeeze(-1)
    return y, y

Round (Module)

A small torch module for rounding the values of an input tensor

Source code in evotorch/neuroevolution/net/layers.py 
class Round(nn.Module):
    """A small torch module for rounding the values of an input tensor"""

    def __init__(self, ndigits: int = 0):
        nn.Module.__init__(self)
        self._ndigits = int(ndigits)
        self._q = 10.0**self._ndigits

    def forward(self, x):
        x = x * self._q
        x = torch.round(x)
        x = x / self._q
        return x

    def extra_repr(self):
        return "ndigits=" + str(self._ndigits)

extra_repr(self)

Set the extra representation of the module

To print customized extra information, you should re-implement this method in your own modules. Both single-line and multi-line strings are acceptable.

Source code in evotorch/neuroevolution/net/layers.py 
def extra_repr(self):
    return "ndigits=" + str(self._ndigits)

forward(self, x)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x):
    x = x * self._q
    x = torch.round(x)
    x = x / self._q
    return x

Slice (Module)

A small torch module for getting the slice of an input tensor

Source code in evotorch/neuroevolution/net/layers.py 
class Slice(nn.Module):
    """A small torch module for getting the slice of an input tensor"""

    def __init__(self, from_index: int, to_index: int):
        """`__init__(...)`: Initialize the Slice operator.

        Args:
            from_index: The index from which the slice begins.
            to_index: The exclusive index at which the slice ends.
        """
        nn.Module.__init__(self)
        self._from_index = from_index
        self._to_index = to_index

    def forward(self, x):
        return x[self._from_index : self._to_index]

    def extra_repr(self):
        return "from_index={}, to_index={}".format(self._from_index, self._to_index)

__init__(self, from_index, to_index) special

__init__(...): Initialize the Slice operator.

Parameters:

Name Type Description Default
from_index int

The index from which the slice begins.

 required
to_index int

The exclusive index at which the slice ends.

 required
Source code in evotorch/neuroevolution/net/layers.py 
def __init__(self, from_index: int, to_index: int):
    """`__init__(...)`: Initialize the Slice operator.

    Args:
        from_index: The index from which the slice begins.
        to_index: The exclusive index at which the slice ends.
    """
    nn.Module.__init__(self)
    self._from_index = from_index
    self._to_index = to_index

extra_repr(self)

Set the extra representation of the module

To print customized extra information, you should re-implement this method in your own modules. Both single-line and multi-line strings are acceptable.

Source code in evotorch/neuroevolution/net/layers.py 
def extra_repr(self):
    return "from_index={}, to_index={}".format(self._from_index, self._to_index)

forward(self, x)

Defines the computation performed at every call.

Should be overridden by all subclasses.

.. note:: Although the recipe for forward pass needs to be defined within this function, one should call the :class:Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x):
    return x[self._from_index : self._to_index]

StructuredControlNet (Module)

Structured Control Net.

This is a control network consisting of two components: (i) a non-linear component, which is a feed-forward network; and (ii) a linear component, which is a linear layer. Both components take the input vector provided to the structured control network. The final output is the sum of the outputs of both components.

Reference

Mario Srouji, Jian Zhang, Ruslan Salakhutdinov (2018). Structured Control Nets for Deep Reinforcement Learning.

Source code in evotorch/neuroevolution/net/layers.py 
class StructuredControlNet(nn.Module):
    """Structured Control Net.

    This is a control network consisting of two components:
    (i) a non-linear component, which is a feed-forward network; and
    (ii) a linear component, which is a linear layer.
    Both components take the input vector provided to the
    structured control network.
    The final output is the sum of the outputs of both components.

    Reference:
        Mario Srouji, Jian Zhang, Ruslan Salakhutdinov (2018).
        Structured Control Nets for Deep Reinforcement Learning.
    """

    def __init__(
        self,
        *,
        in_features: int,
        out_features: int,
        num_layers: int,
        hidden_size: int,
        bias: bool = True,
        nonlinearity: Union[str, Callable] = "tanh",
    ):
        """`__init__(...)`: Initialize the structured control net.

        Args:
            in_features: Length of the input vector
            out_features: Length of the output vector
            num_layers: Number of hidden layers for the non-linear component
            hidden_size: Number of neurons in a hidden layer of the
                non-linear component
            bias: Whether or not the linear component is to have bias
            nonlinearity: Activation function
        """

        nn.Module.__init__(self)

        self._in_features = in_features
        self._out_features = out_features
        self._num_layers = num_layers
        self._hidden_size = hidden_size
        self._bias = bias
        self._nonlinearity = nonlinearity

        self._linear_component = nn.Linear(
            in_features=self._in_features, out_features=self._out_features, bias=self._bias
        )

        self._nonlinear_component = FeedForwardNet(
            input_size=self._in_features,
            layers=(
                list((self._hidden_size, self._nonlinearity) for _ in range(self._num_layers))
                + [(self._out_features, self._nonlinearity)]
            ),
        )

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        """TODO: documentation"""
        return self._linear_component(x) + self._nonlinear_component(x)

    @property
    def in_features(self):
        """TODO: documentation"""
        return self._in_features

    @property
    def out_features(self):
        """TODO: documentation"""
        return self._out_features

    @property
    def num_layers(self):
        """TODO: documentation"""
        return self._num_layers

    @property
    def hidden_size(self):
        """TODO: documentation"""
        return self._hidden_size

    @property
    def bias(self):
        """TODO: documentation"""
        return self._bias

    @property
    def nonlinearity(self):
        """TODO: documentation"""
        return self._nonlinearity

bias property readonly

hidden_size property readonly

in_features property readonly

nonlinearity property readonly

num_layers property readonly

out_features property readonly

__init__(self, *, in_features, out_features, num_layers, hidden_size, bias=True, nonlinearity='tanh') special

__init__(...): Initialize the structured control net.

Parameters:

Name Type Description Default
in_features int

Length of the input vector

 required
out_features int

Length of the output vector

 required
num_layers int

Number of hidden layers for the non-linear component

 required
hidden_size int

Number of neurons in a hidden layer of the non-linear component

 required
bias bool

Whether or not the linear component is to have bias

 True
nonlinearity Union[str, Callable]

Activation function

 'tanh'
Source code in evotorch/neuroevolution/net/layers.py 
def __init__(
    self,
    *,
    in_features: int,
    out_features: int,
    num_layers: int,
    hidden_size: int,
    bias: bool = True,
    nonlinearity: Union[str, Callable] = "tanh",
):
    """`__init__(...)`: Initialize the structured control net.

    Args:
        in_features: Length of the input vector
        out_features: Length of the output vector
        num_layers: Number of hidden layers for the non-linear component
        hidden_size: Number of neurons in a hidden layer of the
            non-linear component
        bias: Whether or not the linear component is to have bias
        nonlinearity: Activation function
    """

    nn.Module.__init__(self)

    self._in_features = in_features
    self._out_features = out_features
    self._num_layers = num_layers
    self._hidden_size = hidden_size
    self._bias = bias
    self._nonlinearity = nonlinearity

    self._linear_component = nn.Linear(
        in_features=self._in_features, out_features=self._out_features, bias=self._bias
    )

    self._nonlinear_component = FeedForwardNet(
        input_size=self._in_features,
        layers=(
            list((self._hidden_size, self._nonlinearity) for _ in range(self._num_layers))
            + [(self._out_features, self._nonlinearity)]
        ),
    )

forward(self, x)

Source code in evotorch/neuroevolution/net/layers.py 
def forward(self, x: torch.Tensor) -> torch.Tensor:
    """TODO: documentation"""
    return self._linear_component(x) + self._nonlinear_component(x)