Python tensor.maximum函数代码示例

  def __init__(self, factor=numpy.sqrt(2), decay=1.0, min_factor=None, padding=False, **kwargs):
    super(ConvFMPLayer, self).__init__(**kwargs)
    if min_factor is None:
      min_factor = factor
    factor = T.maximum(factor * (decay ** self.network.epoch), numpy.float32(min_factor))
    sizes_raw = self.source.output_sizes

    # handle size problems
    if not padding:
      padding = T.min(self.source.output_sizes / factor) <= 0
      padding = theano.printing.Print(global_fn=maybe_print_pad_warning)(padding)

    fixed_sizes = T.maximum(sizes_raw, T.cast(T.as_tensor(
      [factor + self.filter_height - 1, factor + self.filter_width - 1]), 'float32'))
    sizes = ifelse(padding, fixed_sizes, sizes_raw)
    X_size = T.cast(T.max(sizes, axis=0), "int32")

    def pad_fn(x_t, s):
      x = T.alloc(numpy.cast["float32"](0), X_size[0], X_size[1], self.X.shape[3])
      x = T.set_subtensor(x[:s[0], :s[1]], x_t[:s[0], :s[1]])
      return x

    fixed_X, _ = theano.scan(pad_fn, [self.X.dimshuffle(2, 0, 1, 3), T.cast(sizes_raw, "int32")])
    fixed_X = fixed_X.dimshuffle(1, 2, 0, 3)
    self.X = ifelse(padding, T.unbroadcast(fixed_X, 3), self.X)

    conv_out = CuDNNConvHWBCOpValidInstance(self.X, self.W, self.b)
    conv_out_sizes = self.conv_output_size_from_input_size(sizes)
    self.output, self.output_sizes = fmp(conv_out, conv_out_sizes, T.cast(factor,'float32'))

    def grad_init(self):
        mask_ = self.mask.flatten()
        rewards_ = self.rewards.flatten()
        actions_ = self.actions.reshape([self.actions.shape[0]*self.actions.shape[1],-1])

        #self.mov_std = theano.shared(numpy.float32(1.), 'std')

        pp = self.params.values()
        mean_rewards = (mask_ * rewards_).sum(-1, keepdims=True) / tensor.maximum(1., mask_.sum(-1, keepdims=True))
        centered_rewards = rewards_ - self.vapprox.v[:,0] - mean_rewards
        mean2_rewards = (mask_ * (rewards_ ** 2)).sum(-1, keepdims=True) / tensor.maximum(1., mask_.sum(-1, keepdims=True))
        var_rewards = mean2_rewards - (mean_rewards ** 2)
        scaled_rewards = centered_rewards  / tensor.maximum(1., tensor.sqrt(tensor.maximum(0., var_rewards)))
        #scaled_rewards = centered_rewards

        logprob = 0.
        reg = 0.
        for oi in xrange(self.n_out):
            labs = actions_[:,oi].flatten()
            labs_idx = tensor.arange(labs.shape[0]) * self.out_dim + labs
            logprob = logprob + (mask_ * tensor.log(self.pi[oi].flatten()+1e-6)[labs_idx])
            reg = reg - (self.pi[oi] * tensor.log(self.pi[oi]+1e-6)).sum(-1).sum(0)

        self.cost = -tensor.mean(scaled_rewards * logprob + self.reg_c * reg)
        self.grads = tensor.grad(self.cost, wrt=pp)

 def updates(self, cost, params, learning_rate = 0.1, momentum= 0.95, rescale=5.):
     grads = T.grad(cost, params)
     grad_norm = T.sqrt(sum(map(lambda x: T.sqr(x).sum(), grads)))
     not_finite = T.or_(T.isnan(grad_norm), T.isinf(grad_norm))
     grad_norm = T.sqrt(grad_norm)
     scaling_num = rescale
     scaling_den = T.maximum(rescale, grad_norm)
     # Magic constants
     combination_coeff = 0.9
     minimum_grad = 1e-4
     updates = []
     for n, (param, grad) in enumerate(zip(params, grads)):
         grad = T.switch(not_finite, 0.1 * param,
                         grad * (scaling_num / scaling_den))
         old_square = self.running_square_[n]
         new_square = combination_coeff * old_square + (
             1. - combination_coeff) * T.sqr(grad)
         old_avg = self.running_avg_[n]
         new_avg = combination_coeff * old_avg + (
             1. - combination_coeff) * grad
         rms_grad = T.sqrt(new_square - new_avg ** 2)
         rms_grad = T.maximum(rms_grad, minimum_grad)
         memory = self.memory_[n]
         update = momentum * memory - learning_rate * grad / rms_grad
         update2 = momentum * momentum * memory - (
             1 + momentum) * learning_rate * grad / rms_grad
         updates.append((old_square, new_square))
         updates.append((old_avg, new_avg))
         updates.append((memory, update))
         updates.append((param, param + update2))
     return updates

 def infer_shape(self, node, ishapes):
     mus_shape, prior_mu, prior_sigma = ishapes
     return [
         (tensor.maximum(1, mus_shape[0]),),
         (tensor.maximum(1, mus_shape[0]),),
         (tensor.maximum(1, mus_shape[0]),),
     ]

    def _local_error(self, targetM, i):
        pull_error = 0.
        ivectors = self._x[:, i, :][self._neighborpairs[:, 0]]
        jvectors = self._x[:, i, :][self._neighborpairs[:, 1]]
        diffv = ivectors - jvectors
        pull_error = linalg.trace(diffv.dot(targetM).dot(diffv.T))

        push_error = 0.0
        ivectors = self._x[:, i, :][self._set[:, 0]]
        jvectors = self._x[:, i, :][self._set[:, 1]]
        lvectors = self._x[:, i, :][self._set[:, 2]]
        diffij = ivectors - jvectors
        diffil = ivectors - lvectors
        lossij = diffij.dot(targetM).dot(diffij.T)
        lossil = diffil.dot(targetM).dot(diffil.T)
        mask = T.neq(self._y[self._set[:, 0]], self._y[self._set[:, 2]])
        push_error = linalg.trace(mask*T.maximum(lossij - lossil + 1, 0))

        self.zerocount = T.eq(linalg.diag(mask*T.maximum(lossij - lossil + 1, 0)), 0).sum()

#       print np.sqrt((i+1.0)/self.M)
#       pull_error = pull_error * np.sqrt((i+1.0)/self.M)
#       push_error = push_error * np.sqrt((i+1.0)/self.M)

        return pull_error, push_error 

def convolutional_model(X, w_1, w_2, w_3, w_4, w_5, w_6, p_1, p_2, p_3, p_4, p_5):
    l1 = dropout(T.tanh( max_pool_2d(T.maximum(conv2d(X, w_1, border_mode='full'),0.), (2, 2),ignore_border=True) + b_1.dimshuffle('x', 0, 'x', 'x') ), p_1)
    l2 = dropout(T.tanh( max_pool_2d(T.maximum(conv2d(l1, w_2), 0.), (2, 2),ignore_border=True) + b_2.dimshuffle('x', 0, 'x', 'x') ), p_2)
    l3 = dropout(T.flatten(T.tanh( max_pool_2d(T.maximum(conv2d(l2, w_3), 0.), (2, 2),ignore_border=True) + b_3.dimshuffle('x', 0, 'x', 'x') ), outdim=2), p_3)# flatten to switch back to 1d layers
    l4 = dropout(T.maximum(T.dot(l3, w_4), 0.), p_4)
    l5 = dropout(T.maximum(T.dot(l4, w_5), 0.), p_5)
    return T.dot(l5, w_6)

  def cost(self):
    known_grads = None
    xd = self.z.reshape((self.z.shape[0]*self.z.shape[1],self.z.shape[2]))
    epsilon = numpy.float32(1e-10)
    # cross-entropy
    nll, _ = T.nnet.crossentropy_softmax_1hot(x=xd[self.i], y_idx=self.y_data_flat[self.i])
    ce = T.sum(nll)
    # entropy
    def entropy(p, axis=None):
      if self.use_max and axis is not None:
        q = p.dimshuffle(axis, *(range(axis) + range(axis+1,p.ndim)))
        #return -T.mean(T.log(T.maximum(T.max(q,axis=0),epsilon)))
        return -T.mean(T.max(q,axis=0)+epsilon) + T.log(T.cast(p.shape[axis],'float32'))
      else:
        return -T.mean(p*T.log(p+epsilon)) + T.log(T.cast(p.shape[axis],'float32'))
    ez = T.exp(self.z) * T.cast(self.index.dimshuffle(0,1,'x').repeat(self.z.shape[2],axis=2), 'float32')
    et = entropy(ez / T.maximum(epsilon,T.sum(ez,axis=0,keepdims=True)),axis=0)
    eb = entropy(ez / T.maximum(epsilon,T.sum(ez,axis=1,keepdims=True)),axis=1)
    ed = entropy(ez / T.maximum(epsilon,T.sum(ez,axis=2,keepdims=True)),axis=2)
    # maximize entropy across T and B and minimize entropy across D
    e = self.e_d * ed - (self.e_t * et + self.e_b * eb) / numpy.float32(self.e_t + self.e_b)

    import theano.ifelse
    if self.train_flag:
      return theano.ifelse.ifelse(T.cast(self.xflag,'int8'),e,ce), known_grads
    else:
      return ce, known_grads

def advanced_indexing(volume, *indices_list, **kwargs):
    """ Performs advanced indexing on `volume`.

    This function exists because in Theano<=0.9 advanced indexing is
    only supported along the first dimension.

    Notes
    -----
    Assuming `volume` is C contiguous.
    """
    strides = kwargs.get("strides")
    if strides is None:
        shapes = T.cast(volume.shape[:len(indices_list)], dtype=theano.config.floatX)
        strides = T.concatenate([T.ones((1,)), T.cumprod(shapes[::-1])[:-1]], axis=0)[::-1]

    shapes = T.cast(volume.shape, dtype=theano.config.floatX)

    indices = T.maximum(0, T.minimum(indices_list[-1], shapes[len(indices_list)-1]-1))
    for i in range(len(indices_list)-1):
        clipped_idx = T.maximum(0, T.minimum(indices_list[i], shapes[i]-1))
        indices += clipped_idx * strides[i]

    # indices = T.sum(T.stack(indices_list, axis=1)*strides[:len(indices_list)], axis=1)
    indices = T.cast(indices, dtype="int32")
    return volume.reshape((-1, volume.shape[-1]))[indices]

    def init_lpool(self, x, x_shp,
            ker_shape=(3, 3),
            order=1,
            stride=1,
            mode='valid'):

        if hasattr(order, '__iter__'):
            o1 = (order == 1).all()
            o2 = (order == order.astype(np.int)).all()
        else:
            o1 = order == 1
            o2 = (order == int(order))

        if o1:
            r, r_shp = self.boxconv(x, x_shp, ker_shape)
        elif o2:
            r, r_shp = self.boxconv(x ** order, x_shp, ker_shape)
            r = tensor.maximum(r, 0) ** (1.0 / order)
        else:
            r, r_shp = self.boxconv(abs(x) ** order, x_shp, ker_shape)
            r = tensor.maximum(r, 0) ** (1.0 / order)

        if stride > 1:
            r = r[:, :, ::stride, ::stride]
            # intdiv is tricky... so just use numpy
            r_shp = np.empty(r_shp)[:, :, ::stride, ::stride].shape
        return r, r_shp

    def get_updates(self, v):
        # Contrastive divergence
        chain_end, updates_CD = self.CD(self, chain_start=v, cdk=self.CDk)

        # [Expected] negative log-likelihood
        cost = T.mean(self.free_energy(v), axis=0) - T.mean(self.free_energy(chain_end), axis=0)

        # L2 Regularization
        if isinstance(self.regularize, L2Regularization):
            cost += self.regularization

        # Gradients (use automatic differentiation)
        # We must not compute the gradient through the gibbs sampling, i.e. use consider_constant
        gparams = T.grad(cost, self.parameters, consider_constant=[chain_end])
        gradients = dict(zip(self.parameters, gparams))

        # Get learning rates for all params given their gradient.
        lr, updates_lr = self.learning_rate(gradients)

        updates = OrderedDict()
        updates.update(updates_CD)  # Add updates from CD
        updates.update(updates_lr)  # Add updates from learning_rate

        # Updates parameters
        for param, gparam in gradients.items():
            updates[param] = param - lr[param] * gradients[param]

        if isinstance(self.regularize, L1Regularization):
            updates[self.b] = T.sgn(updates[self.b]) * T.maximum(abs(updates[self.b]) - lr[self.b]*self.regularize.decay, 0)
            updates[self.W] = T.sgn(updates[self.W]) * T.maximum(abs(updates[self.W]) - lr[self.W]*self.regularize.decay, 0)

        return updates

    def setup(self, bottom, top):
        from caffe_helper.theano_util import init_theano
        init_theano()

        import theano as tn
        import theano.tensor as T
        assert len(bottom) == 2
        assert len(top) == 1
        s_y = T.matrix('y')  # y in [-inf, inf]
        s_t = T.matrix('t')  # t in {-1, 0, 1} where 0 is ignored
        s_dloss = T.scalar('dloss')
        # Forward
        # s_loss = T.mean(abs(s_t) * T.log1p(T.exp(-s_y * s_t)))  # unstable
        s_loss = -T.sum(
            abs(s_t) * (
                s_y * ((s_t >= 0) - (s_y >= 0)) - T.log1p(T.exp(-abs(s_y)))))\
            / T.maximum(T.sum(abs(s_t)), 1)
        # Backward
        s_p = 1 / (1 + T.exp(-s_y))
        s_dy = s_dloss * abs(s_t) * (s_p - (s_t >= 0)) / \
            T.maximum(T.sum(abs(s_t)), 1)

        def _o(s):
            return tn.Out(s, borrow=True)
        self.tn_forward = tn.function([s_y, s_t], s_loss)
        self.tn_backward = tn.function([s_y, s_t, s_dloss], _o(s_dy))

def tiled_eye(n1, n2, dtype="float32"):
  r1 = T.maximum((n1 - 1) / n2 + 1, 1)
  r2 = T.maximum((n2 - 1) / n1 + 1, 1)
  small_eye = T.eye(T.minimum(n1, n2), dtype=dtype)
  tiled_big = T.tile(small_eye, (r1, r2))
  tiled_part = tiled_big[:n1,:n2]
  return tiled_part

def maxout_func(n_out, last_start, pool_size, rectify, lin_output):
    tmp_output = lin_output[:,0:last_start+1:pool_size]
    for i in range(1, pool_size):
        cur = lin_output[:,i:last_start+i+1:pool_size]
        tmp_output = T.maximum(cur, tmp_output)
    if rectify:
        self.tmp_output = T.maximum(0, self.tmp_output)

    def grad_init(self):
        #self.mov_std = theano.shared(numpy.float32(1.), 'std')

        rewards_ = self.rewards[0]
        mean_rewards = rewards_.mean()
        var_rewards = rewards_.var()

        pp = self.params.values()

        #mean_rewards = (self.mask * self.rewards).sum(-1, keepdims=True) / tensor.maximum(1., self.mask.sum(-1, keepdims=True))
        ##centered_rewards = self.rewards - self.vapprox.v[:,:,0] - mean_rewards
        centered_rewards = rewards_ - mean_rewards - self.vapprox.v[:,0] 
        #mean2_rewards = (self.mask * (self.rewards ** 2)).sum(-1, keepdims=True) / tensor.maximum(1., self.mask.sum(-1, keepdims=True))
        #var_rewards = mean2_rewards - (mean_rewards ** 2)
        scaled_rewards = centered_rewards  / tensor.maximum(1., tensor.sqrt(tensor.maximum(0., var_rewards)))

        logprob = 0.
        reg = 0.
        for oi in xrange(self.n_out):
            labs = self.actions[:,:,oi].flatten()
            labs_idx = tensor.arange(labs.shape[0]) * self.out_dim + labs
            logprob = logprob + ((self.mask * 
                                  tensor.log(self.pi[oi].flatten()+1e-6)[labs_idx]
                                  .reshape([self.actions.shape[0], 
                                            self.actions.shape[1]])).sum(0))
            reg = reg - (self.pi[oi] * tensor.log(self.pi[oi]+1e-6)).sum(-1).sum(0)

        self.cost = -tensor.mean(scaled_rewards * logprob + self.reg_c * reg)
        self.grads = tensor.grad(self.cost, wrt=pp)

    def inner(target, embedding):
        """Return a theano expression of a vector containing the sample wise
        loss of drlim.

        The push_margin, pull_margin and coefficient for the contrastives
        used are %.f, %.f and %.f respectively.

        Parameters
        ----------

        target : array_like
            A vector of length `n`. If 1, sample `2 * n` and sample
            `2 * n + 1` are deemed similar.

        embedding : array_like
            Array containing the embeddings of samples row wise.
        """ % (push_margin, pull_margin, c_contrastive)
        target = target[:, 0]
        n_pair = embedding.shape[0] // 2
        n_feature = embedding.shape[1]

        # Reshape array to get pairs.
        embedding = embedding.reshape((n_pair, n_feature * 2))

        # Calculate distances of pairs.
        diff = (embedding[:, :n_feature] - embedding[:, n_feature:])
        dist = T.sqrt((diff ** 2).sum(axis=1) + 1e-8)

        pull = target * f_pull_loss(T.maximum(0, dist - pull_margin))
        push = (1 - target) * f_push_loss(T.maximum(0, push_margin - dist))

        loss = pull + c_contrastive * push
        return loss.dimshuffle(0, 'x')