Python theano.shared函数代码示例

    def __init__(self, input, n_in, n_out):
        """ Initialize the parameters of the logistic regression

        :type input: theano.tensor.TensorType
        :param input: symbolic variable that describes the input of the
                      architecture (one minibatch)

        :type n_in: int
        :param n_in: number of input units, the dimension of the space in
                     which the datapoints lie

        :type n_out: int
        :param n_out: number of output units, the dimension of the space in
                      which the labels lie

        """

        # initialize with 0 the weights W as a matrix of shape (n_in, n_out)
        self.W = theano.shared(value=numpy.zeros((n_in, n_out),
                                                 dtype=theano.config.floatX),
                                name='W', borrow=True)
        # initialize the baises b as a vector of n_out 0s
        self.b = theano.shared(value=numpy.zeros((n_out,),
                                                 dtype=theano.config.floatX),
                               name='b', borrow=True)

        # compute vector of class-membership probabilities in symbolic form
        self.p_y_given_x = T.nnet.softmax(T.dot(input, self.W) + self.b)

        # compute prediction as class whose probability is maximal in
        # symbolic form
        self.y_pred = T.argmax(self.p_y_given_x, axis=1)

        # parameters of the model
        self.params = [self.W, self.b]

def adam(loss, all_params, learn_rate=0.001, b1=0.9, b2=0.999, e=1e-8, gamma=1-1e-8):
    """ADAM update rules

    Kingma, Diederik, and Jimmy Ba. "Adam: A Method for Stochastic Optimization." arXiv preprint arXiv:1412.6980 (2014). http://arxiv.org/pdf/1412.6980v4.pdf
    """
    updates = []
    all_grads = theano.grad(loss, all_params)
    alpha = learn_rate
    t = theano.shared(np.float32(1.))
    b1_t = b1 * gamma ** (t - 1.)   # decay the first moment running average coefficient

    for theta_prev, g in zip(all_params, all_grads):
        m_prev = theano.shared(np.zeros(theta_prev.get_value().shape, dtype=theano.config.floatX))
        v_prev = theano.shared(np.zeros(theta_prev.get_value().shape, dtype=theano.config.floatX))

        m = b1_t * m_prev + (1. - b1_t) * g  # update biased first moment estimate
        v = b2 * v_prev + (1. - b2) * g ** 2  # update biased second raw moment estimate
        m_hat = m / (1. - b1 ** t)  # compute bias-corrected first moment estimate
        v_hat = v / (1. - b2 ** t)  # compute bias-corrected second raw moment estimate
        theta = theta_prev - (alpha * m_hat) / (T.sqrt(v_hat) + e)  # update parameters

        updates.append((m_prev, m))
        updates.append((v_prev, v))
        updates.append((theta_prev, theta) )
    updates.append((t, t + 1.))
    return updates

    def __init__(self, n_in, n_out, W_init=None, b_init=None,
                 activation=T.tanh):
        self.activation = activation
        if W_init is None:
            rng = numpy.random.RandomState(1234)
            W_values = numpy.asarray(rng.uniform(
                    low=-numpy.sqrt(6. / (n_in + n_out)),
                    high=numpy.sqrt(6. / (n_in + n_out)),
                    size=(n_in, n_out)
                ),
                dtype=theano.config.floatX
            )
            if activation == theano.tensor.nnet.sigmoid:
                W_values *= 4

            W_init = theano.shared(value=W_values, name='W', borrow=True)

        if b_init is None:
            b_values = numpy.zeros((n_out,), dtype=theano.config.floatX)
            b_init = theano.shared(value=b_values, name='b', borrow=True)

        self.W = W_init
        self.b = b_init
        # parameters of the model
        self.params = [self.W, self.b]

 def shared(data):
     """ Place the data into shared variables. This allows Theano to copy
     the data to the GPU, if one is available.
     """
     shared_x = theano.shared(numpy.asarray(data[:,0].tolist(), dtype=theano.config.floatX), borrow=True)
     shared_y = theano.shared(numpy.asarray(data[:,1].tolist(), dtype=theano.config.floatX), borrow=True)
     return shared_x, T.cast(shared_y, "int32")

    def __init__(self, rng, input, n_in, n_out, W=None, b=None,
                 activation=T.tanh):
        self.input = input[0]

        # initialize weights into this layer
        if W is None:
            W_values = np.asarray(
                rng.uniform(
                    size=(n_in, n_out),
                    low=-np.sqrt(6. / (n_in + n_out)),
                    high=np.sqrt(6. / (n_in + n_out)),
                ),
                dtype=theano.config.floatX
            )
            if activation == theano.tensor.nnet.sigmoid:
                W_values *= 4

            W = theano.shared(value=W_values, name='W', borrow=True)

        # initialize bias term weights into this layer
        if b is None:
            b_values = np.zeros((n_out,), dtype=theano.config.floatX)
            b = theano.shared(value=b_values, name='b', borrow=True)

        self.W = W
        self.b = b

        lin_output = T.dot(self.input, self.W) + self.b
        self.output = (
            lin_output if activation is None
            else activation(lin_output)
        )

        self.params = [self.W, self.b]

 def __init__(self, filter_shape, image_shape, poolsize=(2, 2),
              activation_fn=sigmoid):
     """`filter_shape` is a tuple of length 4, whose entries are the number
     of filters, the number of input feature maps, the filter height, and the
     filter width.
     `image_shape` is a tuple of length 4, whose entries are the
     mini-batch size, the number of input feature maps, the image
     height, and the image width.
     `poolsize` is a tuple of length 2, whose entries are the y and
     x pooling sizes.
     """
     self.filter_shape = filter_shape
     self.image_shape = image_shape
     self.poolsize = poolsize
     self.activation_fn=activation_fn
     # initialize weights and biases
     n_out = (filter_shape[0]*np.prod(filter_shape[2:])/np.prod(poolsize))
     self.w = theano.shared(
         np.asarray(
             np.random.normal(loc=0, scale=np.sqrt(1.0/n_out), size=filter_shape),
             dtype=theano.config.floatX),
         borrow=True)
     self.b = theano.shared(
         np.asarray(
             np.random.normal(loc=0, scale=1.0, size=(filter_shape[0],)),
             dtype=theano.config.floatX),
         borrow=True)
     self.params = [self.w, self.b]

    def init_conv_filters(self, numpy_rng, D, poolsize):
        ''' Convolutional Filters '''
        # there are "num input feature maps * filter height * filter width"
        # inputs to each hidden unit
        fan_in = np.prod(self.filter_shape[1:])

        # each unit in the lower layer receives a gradient from:
        # "num output feature maps * filter height * filter width" pooling size
        fan_out = (self.filter_shape[0] * np.prod(self.filter_shape[2:]) /
                   np.prod(poolsize))

        # initialize weights with random weights
        W_bound = np.sqrt(6. / (fan_in + fan_out))

        self.W = theano.shared(
                init_conv_weights(-W_bound, W_bound, \
                        self.filter_shape, numpy_rng),borrow=True, name='W_conv')

        #b_values = np.zeros((self.filter_shape[0],), dtype=theano.config.floatX)
        #self.b = theano.shared(value=b_values, borrow=True, name='b_conv')

        c_values = np.zeros((self.filter_shape[1],), dtype=theano.config.floatX)
        self.c = theano.shared(value=c_values, borrow=True, name='b_conv')

        self.params = [self.W, self.c]

def stack_and_shared(input):
    """
    This will take a list of input variables, turn them into theano shared variables, and return them stacked
    in a single tensor.

    Parameters
    ----------
    input : list or object
        List of input variables to stack into a single shared tensor.

    Returns
    -------
    tensor
        Symbolic tensor of the input variables stacked, or None if input was None.
    """
    if input is None:
        return None
    elif isinstance(input, list):
        shared_ins = []
        for _in in input:
            try:
                shared_ins.append(theano.shared(_in))
            except TypeError as _:
                shared_ins.append(_in)
        return T.stack(shared_ins)
    else:
        try:
            _output = [theano.shared(input)]
        except TypeError as _:
            _output = [input]
        return T.stack(_output)

def check_parameter(name, value):
    parameters = set()
    constants = set()
    observeds = set()

    if isinstance(value, SharedVariable):
        parameters.add(value)
    elif isinstance(value, T.TensorConstant):
        constants.add(value)
    elif isinstance(value, T.TensorVariable):
        inputs = graph.inputs([value])

        for var in inputs:
            if isinstance(var, SharedVariable):
                parameters.add(var)
            elif isinstance(var, T.TensorConstant):
                constants.add(var)
            elif isinstance(var, T.TensorVariable):
                if not var.name:
                    raise ValueError("Observed variables must be named.")
                observeds.add(var)
    else:
        # XXX allow for lists and convert them to ndarray

        if isinstance(value, np.ndarray):
            value = theano.shared(value, name=name)
        else:
            value = theano.shared(float(value), name=name)

        parameters.add(value)

    return value, parameters, constants, observeds

 def setup(self, prev_layer):
     self.input_layer = prev_layer
     self.input = prev_layer.output
     self.W = theano.shared(np.random.random((self.input_layer.output_shape, self.output_shape)).astype(theano.config.floatX)*.01)
     self.b = theano.shared(np.zeros(self.output_shape,dtype=theano.config.floatX))
     self.params = (self.W, self.b)
     self.output = self.activation(T.dot(self.input, self.W) + self.b.dimshuffle('x', 0))

  def __init__(self, kernel, max_iter = 10, max_diff = None):
    """

    :param kernel: a function with a signature (expected, observed) -> a similarity measure
    that accepts symbolic theano expressions and returns them accordingly.
    See `crayimage.hotornot.em.kernels` for examples.
    :param max_iter: maximal number of iteration
    :param max_diff: stop iterations if maximal difference in weights from the previous iteration is smaller than `max_diff`.
    If None the check is not performed.
    """
    self.original_shape = None

    self.kernel = kernel
    self.max_iter = max_iter
    self.max_diff = max_diff

    self.X = theano.shared(
      np.zeros(shape=(0, 0), dtype='float32')
    )

    self.weights = theano.shared(
      np.ones(shape=(0, ), dtype='float32')
    )

    canonical = T.sum(self.weights[:, None] * self.X, axis=0) / T.sum(self.weights)

    weights_updates = self.kernel(canonical, self.X)
    weights_diff = T.max(abs(weights_updates - self.weights))

    upd = {
      self.weights : weights_updates
    }

    self.iteration = theano.function([], weights_diff if max_diff is not None else [], updates=upd)
    self.get_canonical = theano.function([], canonical)

def adadelta(lr, tparams, grads, inp, cost, extra_ups=[], extra_outs=[],
             exclude_params=set([])):
    '''Adadelta'''
    zipped_grads = [theano.shared(p.get_value() * np.float32(0.), name='%s_grad'%k)
                    for k, p in tparams.iteritems()]
    running_up2 = [theano.shared(p.get_value() * np.float32(0.), name='%s_rup2'%k)
                   for k, p in tparams.iteritems()]
    running_grads2 = [theano.shared(p.get_value() * np.float32(0.), name='%s_rgrad2'%k)
                      for k, p in tparams.iteritems()]

    zgup = [(zg, g) for zg, g in zip(zipped_grads, grads)]
    rg2up = [(rg2, 0.95 * rg2 + 0.05 * (g ** 2))
        for rg2, g in zip(running_grads2, grads)]

    f_grad_shared = theano.function(
        inp, [cost]+extra_outs, updates=zgup+rg2up+extra_ups, profile=profile)

    updir = [-T.sqrt(ru2 + 1e-6) / T.sqrt(rg2 + 1e-6) * zg
             for zg, ru2, rg2 in zip(zipped_grads, running_up2, running_grads2)]
    ru2up = [(ru2, 0.95 * ru2 + 0.05 * (ud ** 2))
        for ru2, ud in zip(running_up2, updir)]
    param_up = [(p, p + ud) for p, ud in zip(tools.itemlist(tparams), updir)
        if p.name not in exclude_params]

    if not isinstance(lr, list): lr = [lr]
    f_update = theano.function(lr, [], updates=ru2up+param_up,
        on_unused_input='ignore', profile=profile)

    return f_grad_shared, f_update

    def _init_params(self):
        self.W_hhs = []
        self.W_shortp = []
        for dx in xrange(self.n_layers):
            W_hh = self.init_fn[dx](self.n_hids[(dx-1)%self.n_layers],
                                        self.n_hids[dx],
                                        self.sparsity[dx],
                                        self.scale[dx],
                                        rng=self.rng)
            self.W_hhs.append(theano.shared(value=W_hh, name="W%d_%s" %
                                       (dx,self.name)))

            if dx > 0:
                W_shp = self.init_fn[dx](self.n_hids[self.n_layers-1],
                                         self.n_hids[dx],
                                         self.sparsity[dx],
                                         self.scale[dx],
                                         rng=self.rng)
                self.W_shortp.append(theano.shared(value=W_shp,
                                               name='W_s%d_%s'%(dx,self.name)))
        self.params = [x for x in self.W_hhs] +\
                [x for x in self.W_shortp]

        self.params_grad_scale = [self.grad_scale for x in self.params]
        self.restricted_params = [x for x in self.params]

        if self.weight_noise:
            self.nW_hhs = [theano.shared(x.get_value()*0, name='noise_'+x.name) for x in self.W_hhs]
            self.nW_shortp = [theano.shared(x.get_value()*0, name='noise_'+x.name) for x in self.W_shortp]

            self.noise_params = [x for x in self.nW_hhs] + [x for x in self.nW_shortp]
            self.noise_params_shape_fn = [constant_shape(x.get_value().shape) for x in self.noise_params]

    def __init__(self, network, **kwargs):
        # due to the way that theano handles updates, we cannot update a
        # parameter twice during the same function call. so, instead of handling
        # everything in the updates for self.f_learn(...), we split the
        # parameter updates into two function calls. the first "prepares" the
        # parameters for the gradient computation by moving the entire model one
        # step according to the current velocity. then the second computes the
        # gradient at that new model position and performs the usual velocity
        # and parameter updates.

        self.params = network.params(**kwargs)
        self.momentum = kwargs.get('momentum', 0.5)

        # set up space for temporary variables used during learning.
        self._steps = []
        self._velocities = []
        for param in self.params:
            v = param.get_value()
            n = param.name
            self._steps.append(theano.shared(np.zeros_like(v), name=n + '_step'))
            self._velocities.append(theano.shared(np.zeros_like(v), name=n + '_vel'))

        # step 1. move to the position in parameter space where we want to
        # compute our gradient.
        prepare = []
        for param, step, velocity in zip(self.params, self._steps, self._velocities):
            prepare.append((step, self.momentum * velocity))
            prepare.append((param, param + step))

        logging.info('compiling NAG adjustment function')
        self.f_prepare = theano.function([], [], updates=prepare)

        super(NAG, self).__init__(network, **kwargs)

    def optimizer(loss, param):
        updates = OrderedDict()
        if param is not list:
            param = list(param)

        for param_ in param:
            i = theano.shared(np.array(0, dtype=theano.config.floatX))
            i_int = i.astype('int64')
            value = param_.get_value(borrow=True)
            accu = theano.shared(
                np.zeros(value.shape + (n_win,), dtype=value.dtype))
            grad = tt.grad(loss, param_)

            # Append squared gradient vector to accu_new
            accu_new = tt.set_subtensor(accu[:, i_int], grad ** 2)
            i_new = tt.switch((i + 1) < n_win, i + 1, 0)

            updates[accu] = accu_new
            updates[i] = i_new

            accu_sum = accu_new.sum(axis=1)
            updates[param_] = param_ - (learning_rate * grad /
                                        tt.sqrt(accu_sum + epsilon))

        return updates