AI-MXNet

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lib/AI/MXNet/RNN/Cell.pm  view on Meta::CPAN

    $states : ArrayRef[AI::MXNet::Symbol]
        state to next step of RNN.
    Can be called via overloaded &{}: &{$cell}($inputs, $states);
=cut

method call(AI::MXNet::Symbol $inputs, AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol] $states)
{
    confess("Not Implemented");
}

method _gate_names()
{
    [''];
}

=head2 params

    Parameters of this cell
=cut

method params()
{
    $self->_own_params(0);
    return $self->_params;
}

=head2 state_shape

    shape(s) of states
=cut

method state_shape()
{
    return [map { $_->{shape} } @{ $self->state_info }];
}

=head2 state_info

    shape and layout information of states
=cut

method state_info()
{
    confess("Not Implemented");
}

=head2 begin_state

    Initial state for this cell.

    Parameters
    ----------
    :$func : sub ref, default is AI::MXNet::Symbol->can('zeros')
        Function for creating initial state.
        Can be AI::MXNet::Symbol->can('zeros'),
        AI::MXNet::Symbol->can('uniform'), AI::MXNet::Symbol->can('Variable') etc.
        Use AI::MXNet::Symbol->can('Variable') if you want to directly
        feed the input as states.
    @kwargs :
        more keyword arguments passed to func. For example
        mean, std, dtype, etc.

    Returns
    -------
    $states : ArrayRef[AI::MXNet::Symbol]
        starting states for first RNN step
=cut

method begin_state(CodeRef :$func=AI::MXNet::Symbol->can('zeros'), @kwargs)
{
    assert(
        (not $self->_modified),
        "After applying modifier cells (e.g. DropoutCell) the base "
        ."cell cannot be called directly. Call the modifier cell instead."
    );
    my @states;
    my $func_needs_named_name = $func ne AI::MXNet::Symbol->can('Variable');
    for my $info (@{ $self->state_info })
    {
        $self->_init_counter($self->_init_counter + 1);
        my @name = (sprintf("%sbegin_state_%d", $self->_prefix, $self->_init_counter));
        my %info = %{ $info//{} };
        if($func_needs_named_name)
        {
            unshift(@name, 'name');
        }
        else
        {
            if(exists $info{__layout__})
            {
                $info{kwargs} = { __layout__ => delete $info{__layout__} };
            }
        }
        my %kwargs = (@kwargs, %info);
        my $state = &{$func}(
            'AI::MXNet::Symbol',
            @name,
            %kwargs
        );
        push @states, $state;
    }
    return \@states;
}

=head2 unpack_weights

    Unpack fused weight matrices into separate
    weight matrices

    Parameters
    ----------
    $args : HashRef[AI::MXNet::NDArray]
        hash ref containing packed weights.
        usually from AI::MXNet::Module->get_output()

    Returns
    -------
    $args : HashRef[AI::MXNet::NDArray]
        hash ref with weights associated with
        this cell, unpacked.
=cut

lib/AI/MXNet/RNN/Cell.pm  view on Meta::CPAN

method unroll(
    Int $length,
    Maybe[AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol]] :$inputs=,
    Maybe[AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol]] :$begin_state=,
    Str                                                  :$input_prefix='',
    Str                                                  :$layout='NTC',
    Maybe[Bool]                                          :$merge_outputs=
)
{
    $self->reset;
    my $axis = index($layout, 'T');
    if(not defined $inputs)
    {
        $inputs = [
            map { AI::MXNet::Symbol->Variable("${input_prefix}t${_}_data") } (0..$length-1)
        ];
    }
    elsif(blessed($inputs))
    {
        assert(
            (@{ $inputs->list_outputs() } == 1),
            "unroll doesn't allow grouped symbol as input. Please "
            ."convert to list first or let unroll handle slicing"
        );
        $inputs = AI::MXNet::Symbol->SliceChannel(
            $inputs,
            axis         => $axis,
            num_outputs  => $length,
            squeeze_axis => 1
        );
    }
    else
    {
        assert(@$inputs == $length);
    }
    $begin_state //= $self->begin_state;
    my $states = $begin_state;
    my $outputs;
    my @inputs = @{ $inputs };
    for my $i (0..$length-1)
    {
        my $output;
        ($output, $states) = &{$self}(
            $inputs[$i],
            $states
        );
        push @$outputs, $output;
    }
    if($merge_outputs)
    {
        @$outputs = map { AI::MXNet::Symbol->expand_dims($_, axis => $axis) } @$outputs;
        $outputs = AI::MXNet::Symbol->Concat(@$outputs, dim => $axis);
    }
    return($outputs, $states);
}

method _get_activation($inputs, $activation, @kwargs)
{
    if(not ref $activation)
    {
        return AI::MXNet::Symbol->Activation($inputs, act_type => $activation, @kwargs);
    }
    else
    {
        return &{$activation}($inputs, @kwargs);
    }
}

method _cells_state_shape($cells)
{
    return [map { @{ $_->state_shape } } @$cells];
}

method _cells_state_info($cells)
{
    return [map { @{ $_->state_info } } @$cells];
}

method _cells_begin_state($cells, @kwargs)
{
    return [map { @{ $_->begin_state(@kwargs) } } @$cells];
}

method _cells_unpack_weights($cells, $args)
{
    $args = $_->unpack_weights($args) for @$cells;
    return $args;
}

method _cells_pack_weights($cells, $args)
{
    $args = $_->pack_weights($args) for @$cells;
    return $args;
}

package AI::MXNet::RNN::Cell;
use Mouse;
extends 'AI::MXNet::RNN::Cell::Base';

=head1 NAME

    AI::MXNet::RNN::Cell
=cut

=head1 DESCRIPTION

    Simple recurrent neural network cell

    Parameters
    ----------
    num_hidden : int
        number of units in output symbol
    activation : str or Symbol, default 'tanh'
        type of activation function
    prefix : str, default 'rnn_'
        prefix for name of layers
        (and name of weight if params is undef)
    params : AI::MXNet::RNNParams or undef
        container for weight sharing between cells.
        created if undef.
=cut

has '_num_hidden'  => (is => 'ro', init_arg => 'num_hidden', isa => 'Int', required => 1);
has 'forget_bias'  => (is => 'ro', isa => 'Num');
has '_activation'  => (
    is       => 'ro',
    init_arg => 'activation',
    isa      => 'Activation',
    default  => 'tanh'
);
has '+_prefix'    => (default => 'rnn_');
has [qw/_iW _iB
        _hW _hB/] => (is => 'rw', init_arg => undef);

around BUILDARGS => sub {
    my $orig  = shift;
    my $class = shift;
    return $class->$orig(num_hidden => $_[0]) if @_ == 1;
    return $class->$orig(@_);
};

sub BUILD
{
    my $self = shift;
    $self->_iW($self->params->get('i2h_weight'));
    $self->_iB(
        $self->params->get(
            'i2h_bias',
            (defined($self->forget_bias)
                ? (init => AI::MXNet::LSTMBias->new(forget_bias => $self->forget_bias))
                : ()
            )
        )
    );
    $self->_hW($self->params->get('h2h_weight'));
    $self->_hB($self->params->get('h2h_bias'));
}

method state_info()
{
    return [{ shape => [0, $self->_num_hidden], __layout__ => 'NC' }];
}

method call(AI::MXNet::Symbol $inputs, SymbolOrArrayOfSymbols $states)
{
    $self->_counter($self->_counter + 1);
    my $name = sprintf('%st%d_', $self->_prefix, $self->_counter);
    my $i2h = AI::MXNet::Symbol->FullyConnected(
        data       => $inputs,
        weight     => $self->_iW,
        bias       => $self->_iB,
        num_hidden => $self->_num_hidden,
        name       => "${name}i2h"
    );

lib/AI/MXNet/RNN/Cell.pm  view on Meta::CPAN


    AI::MXNet::RNN::LSTMCell
=cut

=head1 DESCRIPTION

    Long-Short Term Memory (LSTM) network cell.

    Parameters
    ----------
    num_hidden : int
        number of units in output symbol
    prefix : str, default 'lstm_'
        prefix for name of layers
        (and name of weight if params is undef)
    params : AI::MXNet::RNN::Params or None
        container for weight sharing between cells.
        created if undef.
    forget_bias : bias added to forget gate, default 1.0.
        Jozefowicz et al. 2015 recommends setting this to 1.0
=cut

has '+_prefix'     => (default => 'lstm_');
has '+_activation' => (init_arg => undef);
has '+forget_bias' => (is => 'ro', isa => 'Num', default => 1);

method state_info()
{
    return [{ shape => [0, $self->_num_hidden], __layout__ => 'NC' } , { shape => [0, $self->_num_hidden], __layout__ => 'NC' }];
}

method _gate_names()
{
    [qw/_i _f _c _o/];
}

method call(AI::MXNet::Symbol $inputs, SymbolOrArrayOfSymbols $states)
{
    $self->_counter($self->_counter + 1);
    my $name = sprintf('%st%d_', $self->_prefix, $self->_counter);
    my @states = @{ $states };
    my $i2h = AI::MXNet::Symbol->FullyConnected(
        data       => $inputs,
        weight     => $self->_iW,
        bias       => $self->_iB,
        num_hidden => $self->_num_hidden*4,
        name       => "${name}i2h"
    );
    my $h2h = AI::MXNet::Symbol->FullyConnected(
        data       => $states[0],
        weight     => $self->_hW,
        bias       => $self->_hB,
        num_hidden => $self->_num_hidden*4,
        name       => "${name}h2h"
    );
    my $gates = $i2h + $h2h;
    my @slice_gates = @{ AI::MXNet::Symbol->SliceChannel(
        $gates, num_outputs => 4, name => "${name}slice"
    ) };
    my $in_gate = AI::MXNet::Symbol->Activation(
        $slice_gates[0], act_type => "sigmoid", name => "${name}i"
    );
    my $forget_gate = AI::MXNet::Symbol->Activation(
        $slice_gates[1], act_type => "sigmoid", name => "${name}f"
    );
    my $in_transform = AI::MXNet::Symbol->Activation(
        $slice_gates[2], act_type => "tanh", name => "${name}c"
    );
    my $out_gate = AI::MXNet::Symbol->Activation(
        $slice_gates[3], act_type => "sigmoid", name => "${name}o"
    );
    my $next_c = AI::MXNet::Symbol->_plus(
        $forget_gate * $states[1], $in_gate * $in_transform,
        name => "${name}state"
    );
    my $next_h = AI::MXNet::Symbol->_mul(
        $out_gate,
        AI::MXNet::Symbol->Activation(
            $next_c, act_type => "tanh"
        ),
        name => "${name}out"
    );
    return ($next_h, [$next_h, $next_c]);

}

package AI::MXNet::RNN::GRUCell;
use Mouse;
use AI::MXNet::Base;
extends 'AI::MXNet::RNN::Cell';

=head1 NAME

    AI::MXNet::RNN::GRUCell
=cut

=head1 DESCRIPTION

    Gated Rectified Unit (GRU) network cell.
    Note: this is an implementation of the cuDNN version of GRUs
    (slight modification compared to Cho et al. 2014).

    Parameters
    ----------
    num_hidden : int
        number of units in output symbol
    prefix : str, default 'gru_'
        prefix for name of layers
        (and name of weight if params is undef)
    params : AI::MXNet::RNN::Params or undef
        container for weight sharing between cells.
        created if undef.
=cut

has '+_prefix'     => (default => 'gru_');

method _gate_names()
{
    [qw/_r _z _o/];
}

method call(AI::MXNet::Symbol $inputs, SymbolOrArrayOfSymbols $states)
{
    $self->_counter($self->_counter + 1);
    my $name = sprintf('%st%d_', $self->_prefix, $self->_counter);
    my $prev_state_h = @{ $states }[0];
    my $i2h = AI::MXNet::Symbol->FullyConnected(
        data       => $inputs,
        weight     => $self->_iW,
        bias       => $self->_iB,
        num_hidden => $self->_num_hidden*3,
        name       => "${name}i2h"
    );
    my $h2h = AI::MXNet::Symbol->FullyConnected(
        data       => $prev_state_h,
        weight     => $self->_hW,
        bias       => $self->_hB,
        num_hidden => $self->_num_hidden*3,
        name       => "${name}h2h"
    );
    my ($i2h_r, $i2h_z);
    ($i2h_r, $i2h_z, $i2h) = @{ AI::MXNet::Symbol->SliceChannel(
        $i2h, num_outputs => 3, name => "${name}_i2h_slice"
    ) };
    my ($h2h_r, $h2h_z);
    ($h2h_r, $h2h_z, $h2h) = @{ AI::MXNet::Symbol->SliceChannel(
        $h2h, num_outputs => 3, name => "${name}_h2h_slice"
    ) };
    my $reset_gate = AI::MXNet::Symbol->Activation(
        $i2h_r + $h2h_r, act_type => "sigmoid", name => "${name}_r_act"
    );
    my $update_gate = AI::MXNet::Symbol->Activation(
        $i2h_z + $h2h_z, act_type => "sigmoid", name => "${name}_z_act"
    );
    my $next_h_tmp = AI::MXNet::Symbol->Activation(
        $i2h + $reset_gate * $h2h, act_type => "tanh", name => "${name}_h_act"
    );
    my $next_h = AI::MXNet::Symbol->_plus(
        (1 - $update_gate) * $next_h_tmp, $update_gate * $prev_state_h,
        name => "${name}out"
    );
    return ($next_h, [$next_h]);
}

package AI::MXNet::RNN::FusedCell;
use Mouse;
use AI::MXNet::Types;
use AI::MXNet::Base;
extends 'AI::MXNet::RNN::Cell::Base';

=head1 NAME

    AI::MXNet::RNN::FusedCell
=cut

=head1 DESCRIPTION

    Fusing RNN layers across time step into one kernel.
    Improves speed but is less flexible. Currently only
    supported if using cuDNN on GPU.
=cut

has '_num_hidden'      => (is => 'ro', isa => 'Int',  init_arg => 'num_hidden',     required => 1);
has '_num_layers'      => (is => 'ro', isa => 'Int',  init_arg => 'num_layers',     default => 1);
has '_dropout'         => (is => 'ro', isa => 'Num',  init_arg => 'dropout',        default => 0);
has '_get_next_state'  => (is => 'ro', isa => 'Bool', init_arg => 'get_next_state', default => 0);
has '_bidirectional'   => (is => 'ro', isa => 'Bool', init_arg => 'bidirectional',  default => 0);
has 'forget_bias'      => (is => 'ro', isa => 'Num',  default => 1);
has 'initializer'      => (is => 'rw', isa => 'Maybe[Initializer]');
has '_mode'            => (
    is => 'ro',
    isa => enum([qw/rnn_relu rnn_tanh lstm gru/]),
    init_arg => 'mode',
    default => 'lstm'
);
has [qw/_parameter
        _directions/] => (is => 'rw', init_arg => undef);

around BUILDARGS => sub {
    my $orig  = shift;
    my $class = shift;
    return $class->$orig(num_hidden => $_[0]) if @_ == 1;
    return $class->$orig(@_);
};

sub BUILD
{
    my $self = shift;
    if(not $self->_prefix)
    {
        $self->_prefix($self->_mode.'_');
    }
    if(not defined $self->initializer)
    {
        $self->initializer(
            AI::MXNet::Xavier->new(
                factor_type => 'in',
                magnitude   => 2.34
            )
        );
    }
    if(not $self->initializer->isa('AI::MXNet::FusedRNN'))
    {
        $self->initializer(
            AI::MXNet::FusedRNN->new(
                init           => $self->initializer,
                num_hidden     => $self->_num_hidden,
                num_layers     => $self->_num_layers,
                mode           => $self->_mode,
                bidirectional  => $self->_bidirectional,
                forget_bias    => $self->forget_bias
            )
        );
    }
    $self->_parameter($self->params->get('parameters', init => $self->initializer));
    $self->_directions($self->_bidirectional ? [qw/l r/] : ['l']);
}


method state_info()
{
    my $b = @{ $self->_directions };
    my $n = $self->_mode eq 'lstm' ? 2 : 1;
    return [map { +{ shape => [$b*$self->_num_layers, 0, $self->_num_hidden], __layout__ => 'LNC' } } 0..$n-1];
}

method _gate_names()
{
    return {
        rnn_relu => [''],
        rnn_tanh => [''],
        lstm     => [qw/_i _f _c _o/],
        gru      => [qw/_r _z _o/]
    }->{ $self->_mode };
}

method _num_gates()
{
    return scalar(@{ $self->_gate_names })
}

method _slice_weights($arr, $li, $lh)
{
    my %args;
    my @gate_names = @{ $self->_gate_names };
    my @directions = @{ $self->_directions };

    my $b = @directions;
    my $p = 0;
    for my $layer (0..$self->_num_layers-1)
    {
        for my $direction (@directions)
        {
            for my $gate (@gate_names)
            {
                my $name = sprintf('%s%s%d_i2h%s_weight', $self->_prefix, $direction, $layer, $gate);
                my $size;

lib/AI/MXNet/RNN/Cell.pm  view on Meta::CPAN

                {
                    $size = $li*$lh;
                    $args{$name} = $arr->slice([$p,$p+$size-1])->reshape([$lh, $li]);
                }
                $p += $size;
            }
            for my $gate (@gate_names)
            {
                my $name = sprintf('%s%s%d_h2h%s_weight', $self->_prefix, $direction, $layer, $gate);
                my $size = $lh**2;
                $args{$name} = $arr->slice([$p,$p+$size-1])->reshape([$lh, $lh]);
                $p += $size;
            }
        }
    }
    for my $layer (0..$self->_num_layers-1)
    {
        for my $direction (@directions)
        {
            for my $gate (@gate_names)
            {
                my $name = sprintf('%s%s%d_i2h%s_bias', $self->_prefix, $direction, $layer, $gate);
                $args{$name} = $arr->slice([$p,$p+$lh-1]);
                $p += $lh;
            }
            for my $gate (@gate_names)
            {
                my $name = sprintf('%s%s%d_h2h%s_bias', $self->_prefix, $direction, $layer, $gate);
                $args{$name} = $arr->slice([$p,$p+$lh-1]);
                $p += $lh;
            }
        }
    }
    assert($p == $arr->size, "Invalid parameters size for FusedRNNCell");
    return %args;
}

method unpack_weights(HashRef[AI::MXNet::NDArray] $args)
{
    my %args = %{ $args };
    my $arr = delete $args{ $self->_parameter->name };
    my $b = @{ $self->_directions };
    my $m = $self->_num_gates;
    my $h = $self->_num_hidden;
    my $num_input = int(int(int($arr->size/$b)/$h)/$m) - ($self->_num_layers - 1)*($h+$b*$h+2) - $h - 2;
    my %nargs = $self->_slice_weights($arr, $num_input, $self->_num_hidden);
    %args = (%args, map { $_ => $nargs{$_}->copy } keys %nargs);
    return \%args
}

method pack_weights(HashRef[AI::MXNet::NDArray] $args)
{
    my %args = %{ $args };
    my $b = @{ $self->_directions };
    my $m = $self->_num_gates;
    my @c = @{ $self->_gate_names };
    my $h = $self->_num_hidden;
    my $w0 = $args{ sprintf('%sl0_i2h%s_weight', $self->_prefix, $c[0]) };
    my $num_input = $w0->shape->[1];
    my $total = ($num_input+$h+2)*$h*$m*$b + ($self->_num_layers-1)*$m*$h*($h+$b*$h+2)*$b;
    my $arr = AI::MXNet::NDArray->zeros([$total], ctx => $w0->context, dtype => $w0->dtype);
    my %nargs = $self->_slice_weights($arr, $num_input, $h);
    while(my ($name, $nd) = each %nargs)
    {
        $nd .= delete $args{ $name };
    }
    $args{ $self->_parameter->name } = $arr;
    return \%args;
}

method call(AI::MXNet::Symbol $inputs, SymbolOrArrayOfSymbols $states)
{
    confess("AI::MXNet::RNN::FusedCell cannot be stepped. Please use unroll");
}

method unroll(
    Int $length,
    Maybe[AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol]] :$inputs=,
    Maybe[AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol]] :$begin_state=,
    Str                                                  :$input_prefix='',
    Str                                                  :$layout='NTC',
    Maybe[Bool]                                          :$merge_outputs=
)
{
    $self->reset;
    my $axis = index($layout, 'T');
    $inputs //= AI::MXNet::Symbol->Variable("${input_prefix}data");
    if(blessed($inputs))
    {
        assert(
            (@{ $inputs->list_outputs() } == 1),
            "unroll doesn't allow grouped symbol as input. Please "
            ."convert to list first or let unroll handle slicing"
        );
        if($axis == 1)
        {
            AI::MXNet::Logging->warning(
                "NTC layout detected. Consider using "
                ."TNC for RNN::FusedCell for faster speed"
            );
            $inputs = AI::MXNet::Symbol->SwapAxis($inputs, dim1 => 0, dim2 => 1);
        }
        else
        {
            assert($axis == 0, "Unsupported layout $layout");
        }
    }
    else
    {
        assert(@$inputs == $length);
        $inputs = [map { AI::MXNet::Symbol->expand_dims($_, axis => 0) } @{ $inputs }];
        $inputs = AI::MXNet::Symbol->Concat(@{ $inputs }, dim => 0);
    }
    $begin_state //= $self->begin_state;
    my $states = $begin_state;
    my @states = @{ $states };
    my %states;
    if($self->_mode eq 'lstm')
    {
        %states = (state => $states[0], state_cell => $states[1]);
    }

lib/AI/MXNet/RNN/Cell.pm  view on Meta::CPAN

    my $data = AI::MXNet::Symbol->Variable('data');
    my $state_shape = AI::MXNet::Symbol->Convolution(
        data => $data,
        num_filter => $self->_num_hidden,
        kernel => $self->_i2h_kernel,
        stride => $self->_i2h_stride,
        pad => $self->_i2h_pad,
        dilate => $self->_i2h_dilate,
        layout => $self->_conv_layout
    );
    $state_shape = ($state_shape->infer_shape(data=>$self->_input_shape))[1]->[0];
    $state_shape->[0] = 0;
    $self->_state_shape($state_shape);
}

method state_info()
{
    return [
                { shape => $self->_state_shape, __layout__ => $self->_conv_layout },
                { shape => $self->_state_shape, __layout__ => $self->_conv_layout }
    ];
}

method call($inputs, $states)
{
    confess("AI::MXNet::RNN::ConvCell::Base is abstract class for convolutional RNN");
}

package AI::MXNet::RNN::ConvCell;
use Mouse;
extends 'AI::MXNet::RNN::ConvCell::Base';

=head1 NAME

    AI::MXNet::RNN::ConvCell
=cut

=head1 DESCRIPTION

    Convolutional RNN cells

    Parameters
    ----------
    input_shape : array ref of int
        Shape of input in single timestep.
    num_hidden : int
        Number of units in output symbol.
    h2h_kernel : array ref of int, default (3, 3)
        Kernel of Convolution operator in state-to-state transitions.
    h2h_dilate : array ref of int, default (1, 1)
        Dilation of Convolution operator in state-to-state transitions.
    i2h_kernel : array ref of int, default (3, 3)
        Kernel of Convolution operator in input-to-state transitions.
    i2h_stride : array ref of int, default (1, 1)
        Stride of Convolution operator in input-to-state transitions.
    i2h_pad : array ref of int, default (1, 1)
        Pad of Convolution operator in input-to-state transitions.
    i2h_dilate : array ref of int, default (1, 1)
        Dilation of Convolution operator in input-to-state transitions.
    activation : str or Symbol,
        default functools.partial(symbol.LeakyReLU, act_type='leaky', slope=0.2)
        Type of activation function.
    prefix : str, default 'ConvRNN_'
        Prefix for name of layers (and name of weight if params is None).
    params : RNNParams, default None
        Container for weight sharing between cells. Created if None.
    conv_layout : str, , default 'NCHW'
        Layout of ConvolutionOp
=cut

has '+_h2h_kernel' => (default => sub { [3, 3] });
has '+_h2h_dilate' => (default => sub { [1, 1] });
has '+_i2h_kernel' => (default => sub { [3, 3] });
has '+_i2h_stride' => (default => sub { [1, 1] });
has '+_i2h_dilate' => (default => sub { [1, 1] });
has '+_i2h_pad'    => (default => sub { [1, 1] });
has '+_prefix'     => (default => 'ConvRNN_');
has '+_activation' => (default => sub { sub { AI::MXNet::Symbol->LeakyReLU(@_, act_type => 'leaky', slope => 0.2) } });
has '+i2h_bias_initializer' => (default => 'zeros');
has '+h2h_bias_initializer' => (default => 'zeros');
has 'forget_bias'  => (is => 'ro', isa => 'Num');
has [qw/_iW _iB
        _hW _hB/] => (is => 'rw', init_arg => undef);


sub BUILD
{
    my $self = shift;
    $self->_iW($self->_params->get('i2h_weight', init => $self->i2h_weight_initializer));
    $self->_hW($self->_params->get('h2h_weight', init => $self->h2h_weight_initializer));
    $self->_iB(
        $self->params->get(
            'i2h_bias',
            (defined($self->forget_bias and not defined $self->i2h_bias_initializer)
                ? (init => AI::MXNet::LSTMBias->new(forget_bias => $self->forget_bias))
                : (init => $self->i2h_bias_initializer)
            )
        )
    );
    $self->_hB($self->_params->get('h2h_bias', init => $self->h2h_bias_initializer));
}

method _num_gates()
{
    scalar(@{ $self->_gate_names() });
}

method _gate_names()
{
    return ['']
}

method _conv_forward($inputs, $states, $name)
{
    my $i2h = AI::MXNet::Symbol->Convolution(
        name       => "${name}i2h",
        data       => $inputs,
        num_filter => $self->_num_hidden*$self->_num_gates(),
        kernel     => $self->_i2h_kernel,
        stride     => $self->_i2h_stride,
        pad        => $self->_i2h_pad,
        dilate     => $self->_i2h_dilate,
        weight     => $self->_iW,
        bias       => $self->_iB
    );
    my $h2h = AI::MXNet::Symbol->Convolution(
        name       => "${name}h2h",
        data       => @{ $states }[0],
        num_filter => $self->_num_hidden*$self->_num_gates(),
        kernel     => $self->_h2h_kernel,
        stride     => [1, 1],
        pad        => $self->_h2h_pad,
        dilate     => $self->_h2h_dilate,
        weight     => $self->_hW,
        bias       => $self->_hB
    );
    return ($i2h, $h2h);
}

method call(AI::MXNet::Symbol $inputs, AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol] $states)
{
    $self->_counter($self->_counter + 1);
    my $name = sprintf('%st%d_', $self->_prefix, $self->_counter);
    my ($i2h, $h2h) = $self->_conv_forward($inputs, $states, $name);
    my $output = $self->_get_activation($i2h + $h2h, $self->_activation, name => "${name}out");
    return ($output, [$output]);
}

package AI::MXNet::RNN::ConvLSTMCell;
use Mouse;
extends 'AI::MXNet::RNN::ConvCell';
has '+forget_bias' => (default => 1);
has '+_prefix'     => (default => 'ConvLSTM_');

=head1 NAME

    AI::MXNet::RNN::ConvLSTMCell
=cut

=head1 DESCRIPTION

    Convolutional LSTM network cell.

    Reference:
        Xingjian et al. NIPS2015
=cut

method _gate_names()
{
    return ['_i', '_f', '_c', '_o'];
}

method call(AI::MXNet::Symbol $inputs, AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol] $states)
{
    $self->_counter($self->_counter + 1);
    my $name = sprintf('%st%d_', $self->_prefix, $self->_counter);
    my ($i2h, $h2h) = $self->_conv_forward($inputs, $states, $name);
    my $gates = $i2h + $h2h;
    my @slice_gates = @{ AI::MXNet::Symbol->SliceChannel(
        $gates,
        num_outputs => 4,
        axis => index($self->_conv_layout, 'C'),
        name => "${name}slice"
    ) };
    my $in_gate = AI::MXNet::Symbol->Activation(
        $slice_gates[0],
        act_type => "sigmoid",
        name => "${name}i"
    );
    my $forget_gate = AI::MXNet::Symbol->Activation(
        $slice_gates[1],
        act_type => "sigmoid",
        name => "${name}f"
    );
    my $in_transform = $self->_get_activation(
        $slice_gates[2],
        $self->_activation,
        name => "${name}c"
    );
    my $out_gate = AI::MXNet::Symbol->Activation(
        $slice_gates[3],
        act_type => "sigmoid",
        name => "${name}o"
    );
    my $next_c = AI::MXNet::Symbol->_plus(
        $forget_gate * @{$states}[1],
        $in_gate * $in_transform,
        name => "${name}state"
    );
    my $next_h = AI::MXNet::Symbol->_mul(
        $out_gate, $self->_get_activation($next_c, $self->_activation),
        name => "${name}out"
    );
    return ($next_h, [$next_h, $next_c]);
}

package AI::MXNet::RNN::ConvGRUCell;
use Mouse;
extends 'AI::MXNet::RNN::ConvCell';
has '+_prefix'     => (default => 'ConvGRU_');

=head1 NAME

    AI::MXNet::RNN::ConvGRUCell
=cut

=head1 DESCRIPTION

    Convolutional GRU network cell.
=cut

method _gate_names()
{
    return ['_r', '_z', '_o'];
}

method call(AI::MXNet::Symbol $inputs, AI::MXNet::Symbol|ArrayRef[AI::MXNet::Symbol] $states)
{
    $self->_counter($self->_counter + 1);
    my $name = sprintf('%st%d_', $self->_prefix, $self->_counter);
    my ($i2h, $h2h) = $self->_conv_forward($inputs, $states, $name);
    my ($i2h_r, $i2h_z, $h2h_r, $h2h_z);
    ($i2h_r, $i2h_z, $i2h) = @{ AI::MXNet::Symbol->SliceChannel($i2h, num_outputs => 3, name => "${name}_i2h_slice") };
    ($h2h_r, $h2h_z, $h2h) = @{ AI::MXNet::Symbol->SliceChannel($h2h, num_outputs => 3, name => "${name}_h2h_slice") };
    my $reset_gate = AI::MXNet::Symbol->Activation(
        $i2h_r + $h2h_r, act_type => "sigmoid",
        name => "${name}_r_act"
    );
    my $update_gate = AI::MXNet::Symbol->Activation(
        $i2h_z + $h2h_z, act_type => "sigmoid",
        name => "${name}_z_act"
    );
    my $next_h_tmp = $self->_get_activation($i2h + $reset_gate * $h2h, $self->_activation, name => "${name}_h_act");
    my $next_h = AI::MXNet::Symbol->_plus(
        (1 - $update_gate) * $next_h_tmp, $update_gate * @{$states}[0],
        name => "${name}out"
    );
    return ($next_h, [$next_h]);
}

package AI::MXNet::RNN::ModifierCell;
use Mouse;
use AI::MXNet::Base;
extends 'AI::MXNet::RNN::Cell::Base';

=head1 NAME

    AI::MXNet::RNN::ModifierCell
=cut

=head1 DESCRIPTION

    Base class for modifier cells. A modifier
    cell takes a base cell, apply modifications
    on it (e.g. Dropout), and returns a new cell.

    After applying modifiers the base cell should
    no longer be called directly. The modifer cell
    should be used instead.
=cut

has 'base_cell' => (is => 'ro', isa => 'AI::MXNet::RNN::Cell::Base', required => 1);

around BUILDARGS => sub {
    my $orig  = shift;
    my $class = shift;
    if(@_%2)
    {
        my $base_cell = shift;
        return $class->$orig(base_cell => $base_cell, @_);
    }
    return $class->$orig(@_);
};

sub BUILD
{
    my $self = shift;
    $self->base_cell->_modified(1);
}

method params()
{
    $self->_own_params(0);
    return $self->base_cell->params;
}

method state_info()
{
    return $self->base_cell->state_info;
}



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