python类to_float()的实例源码

def ae(x):
    if nonlinearity_name == 'relu':
        f = tf.nn.relu
    elif nonlinearity_name == 'elu':
        f = tf.nn.elu
    elif nonlinearity_name == 'gelu':
        # def gelu(x):
        #     return tf.mul(x, tf.erfc(-x / tf.sqrt(2.)) / 2.)
        # f = gelu
        def gelu_fast(_x):
            return 0.5 * _x * (1 + tf.tanh(tf.sqrt(2 / np.pi) * (_x + 0.044715 * tf.pow(_x, 3))))
        f = gelu_fast
    elif nonlinearity_name == 'silu':
        def silu(_x):
            return _x * tf.sigmoid(_x)
        f = silu
    # elif nonlinearity_name == 'soi':
    #     def soi_map(x):
    #         u = tf.random_uniform(tf.shape(x))
    #         mask = tf.to_float(tf.less(u, (1 + tf.erf(x / tf.sqrt(2.))) / 2.))
    #         return tf.cond(is_training, lambda: tf.mul(mask, x),
    #                        lambda: tf.mul(x, tf.erfc(-x / tf.sqrt(2.)) / 2.))
    #     f = soi_map

    else:
        raise NameError("Need 'relu', 'elu', 'gelu', or 'silu' for nonlinearity_name")

    h1 = f(tf.matmul(x, W['1']) + b['1'])
    h2 = f(tf.matmul(h1, W['2']) + b['2'])
    h3 = f(tf.matmul(h2, W['3']) + b['3'])
    h4 = f(tf.matmul(h3, W['4']) + b['4'])
    h5 = f(tf.matmul(h4, W['5']) + b['5'])
    h6 = f(tf.matmul(h5, W['6']) + b['6'])
    h7 = f(tf.matmul(h6, W['7']) + b['7'])
    return tf.matmul(h7, W['8']) + b['8']

def compute_loss(self, decoder_output, _features, labels):
    """Computes the loss for this model.

    Returns a tuple `(losses, loss)`, where `losses` are the per-batch
    losses and loss is a single scalar tensor to minimize.
    """
    #pylint: disable=R0201
    # Calculate loss per example-timestep of shape [B, T]
    losses = seq2seq_losses.cross_entropy_sequence_loss(
        logits=decoder_output.logits[:, :, :],
        targets=tf.transpose(labels["target_ids"][:, 1:], [1, 0]),
        sequence_length=labels["target_len"] - 1)

    # Calculate the average log perplexity
    loss = tf.reduce_sum(losses) / tf.to_float(
        tf.reduce_sum(labels["target_len"] - 1))

    return losses, loss

def encode(self, inputs):
    inputs = tf.image.resize_images(
        images=inputs,
        size=[self.params["resize_height"], self.params["resize_width"]],
        method=tf.image.ResizeMethod.BILINEAR)

    outputs, _ = inception_v3_base(tf.to_float(inputs))
    output_shape = outputs.get_shape()  #pylint: disable=E1101
    shape_list = output_shape.as_list()

    # Take attentin over output elemnts in width and height dimension:
    # Shape: [B, W*H, ...]
    outputs_flat = tf.reshape(outputs, [shape_list[0], -1, shape_list[-1]])

    # Final state is the pooled output
    # Shape: [B, W*H*...]
    final_state = tf.contrib.slim.avg_pool2d(
        outputs, output_shape[1:3], padding="VALID", scope="pool")
    final_state = tf.contrib.slim.flatten(outputs, scope="flatten")

    return EncoderOutput(
        outputs=outputs_flat,
        final_state=final_state,
        attention_values=outputs_flat,
        attention_values_length=tf.shape(outputs_flat)[1])

def _add_mh_correction(self, initial_position, initial_velocity, final_position, final_velocity):
        """ Applies MH accept/reject correction. """
        initial_energy = self._hamiltonian(initial_position, initial_velocity)
        final_energy = self._hamiltonian(final_position, final_velocity)
        accepted = self._metropolis_hastings_accept(initial_energy, final_energy)
        accepted = tf.to_float(accepted)

        # add acceptance to fetched values
        self._accepted = accepted

        if self.seek_step_sizes or self.fade_in_velocities:
            burned_in = tf.to_float(self._burn_in_ratio == 1)
            accepted = accepted * burned_in + tf.ones(shape=tf.shape(accepted)) * (1 - burned_in)

        # apply MH decision
        final_position = self._transpose_mul(final_position, accepted) + \
                         self._transpose_mul(initial_position, tf.ones(shape=tf.shape(accepted)) - accepted)

        final_velocity = self._transpose_mul(final_velocity, accepted) + \
                         self._transpose_mul(-initial_velocity, tf.ones(shape=tf.shape(accepted)) - accepted)

        return final_position, final_velocity

def mu_law_encode_nonlinear(audio, quantization_channels=256):
    '''
    Compress the waveform amplitudes using mu-law non-linearity. 
    NOTE: This mu-law functions as a non-linear function as opposed to 
          quantization.
    '''
    with tf.name_scope('encode'):
        mu = tf.to_float(quantization_channels - 1)
        # Perform mu-law companding transformation (ITU-T, 1988).
        # Minimum operation is here to deal with rare large amplitudes caused
        # by resampling.
        safe_audio_abs = tf.minimum(tf.abs(audio), 1.0)
        magnitude = tf.log1p(mu * safe_audio_abs) / tf.log1p(mu)
        signal = tf.multiply(tf.sign(audio), magnitude, name='mulaw')
        # Quantize signal to the specified number of levels.
        # return tf.to_int32((signal + 1) / 2 * mu + 0.5)
        return signal

def _crop_pool_layer(self, bottom, rois, name):
    with tf.variable_scope(name) as scope:
      batch_ids = tf.squeeze(tf.slice(rois, [0, 0], [-1, 1], name="batch_id"), [1])
      # Get the normalized coordinates of bboxes
      bottom_shape = tf.shape(bottom)
      height = (tf.to_float(bottom_shape[1]) - 1.) * np.float32(self._feat_stride[0])
      width = (tf.to_float(bottom_shape[2]) - 1.) * np.float32(self._feat_stride[0])
      x1 = tf.slice(rois, [0, 1], [-1, 1], name="x1") / width
      y1 = tf.slice(rois, [0, 2], [-1, 1], name="y1") / height
      x2 = tf.slice(rois, [0, 3], [-1, 1], name="x2") / width
      y2 = tf.slice(rois, [0, 4], [-1, 1], name="y2") / height
      # Won't be back-propagated to rois anyway, but to save time
      bboxes = tf.stop_gradient(tf.concat([y1, x1, y2, x2], 1))
      if cfg.RESNET.MAX_POOL:
        pre_pool_size = cfg.POOLING_SIZE * 2
        crops = tf.image.crop_and_resize(bottom, bboxes, tf.to_int32(batch_ids), [pre_pool_size, pre_pool_size],
                                         name="crops")
        crops = slim.max_pool2d(crops, [2, 2], padding='SAME')
      else:
        crops = tf.image.crop_and_resize(bottom, bboxes, tf.to_int32(batch_ids), [cfg.POOLING_SIZE, cfg.POOLING_SIZE],
                                         name="crops")
    return crops

  # Do the first few layers manually, because 'SAME' padding can behave inconsistently
  # for images of different sizes: sometimes 0, sometimes 1

def _smooth_l1_loss(self, bbox_pred, bbox_targets, bbox_inside_weights, bbox_outside_weights, sigma=1.0, dim=[1]):
    sigma_2 = sigma ** 2
    box_diff = bbox_pred - bbox_targets
    in_box_diff = bbox_inside_weights * box_diff
    abs_in_box_diff = tf.abs(in_box_diff)
    smoothL1_sign = tf.stop_gradient(tf.to_float(tf.less(abs_in_box_diff, 1. / sigma_2)))
    in_loss_box = tf.pow(in_box_diff, 2) * (sigma_2 / 2.) * smoothL1_sign \
                  + (abs_in_box_diff - (0.5 / sigma_2)) * (1. - smoothL1_sign)
    out_loss_box = bbox_outside_weights * in_loss_box
    loss_box = tf.reduce_mean(tf.reduce_sum(
      out_loss_box,
      axis=dim
    ))
    return loss_box

def _crop_pool_layer(self, bottom, rois, name):
    with tf.variable_scope(name) as scope:
      batch_ids = tf.squeeze(tf.slice(rois, [0, 0], [-1, 1], name="batch_id"), [1])
      # Get the normalized coordinates of bounding boxes
      bottom_shape = tf.shape(bottom)
      height = (tf.to_float(bottom_shape[1]) - 1.) * np.float32(self._feat_stride[0])
      width = (tf.to_float(bottom_shape[2]) - 1.) * np.float32(self._feat_stride[0])
      x1 = tf.slice(rois, [0, 1], [-1, 1], name="x1") / width
      y1 = tf.slice(rois, [0, 2], [-1, 1], name="y1") / height
      x2 = tf.slice(rois, [0, 3], [-1, 1], name="x2") / width
      y2 = tf.slice(rois, [0, 4], [-1, 1], name="y2") / height
      # Won't be back-propagated to rois anyway, but to save time
      bboxes = tf.stop_gradient(tf.concat([y1, x1, y2, x2], axis=1))
      pre_pool_size = cfg.POOLING_SIZE * 2
      crops = tf.image.crop_and_resize(bottom, bboxes, tf.to_int32(batch_ids), [pre_pool_size, pre_pool_size], name="crops")

    return slim.max_pool2d(crops, [2, 2], padding='SAME')

def get_label_queue(self,batch_size):
        tf_labels = tf.convert_to_tensor(self.attr.values, dtype=tf.uint8)#0,1

        with tf.name_scope('label_queue'):
            uint_label=tf.train.slice_input_producer([tf_labels])[0]
        label=tf.to_float(uint_label)

        #All labels, not just those in causal_model
        dict_data={sl:tl for sl,tl in
                   zip(self.label_names,tf.split(label,len(self.label_names)))}


        num_preprocess_threads = max(self.num_worker-3,1)

        data_batch = tf.train.shuffle_batch(
                dict_data,
                batch_size=batch_size,
                num_threads=num_preprocess_threads,
                capacity=self.min_queue_examples + 3 * batch_size,
                min_after_dequeue=self.min_queue_examples,
                )

        return data_batch

def l2_loss(tensor, weight=1.0, scope=None, normalize=False):
  """Define a L2Loss, useful for regularize, i.e. weight decay.

  Args:
    tensor: tensor to regularize.
    weight: an optional weight to modulate the loss.
    scope: Optional scope for op_scope.

  Returns:
    the L2 loss op.
  """
  with tf.op_scope([tensor], scope, 'L2Loss'):
    weight = tf.convert_to_tensor(weight,
                                  dtype=tensor.dtype.base_dtype,
                                  name='loss_weight')
    if normalize:
      loss = tf.sqrt( (tf.sqrt( tf.nn.l2_loss(tensor)) / tf.to_float(tf.size(tensor)))  , name='value')
    else:
      loss = tf.mul(weight, tf.nn.l2_loss(tensor), name='value')

    tf.add_to_collection(LOSSES_COLLECTION, loss)
    return loss

def smoothing_cross_entropy(self,logits, labels, vocab_size, confidence=0.9): #confidence = 1.0 - label_smoothing. where label_smooth=0.1. from http://github.com/tensorflow/tensor2tensor
        """Cross entropy with label smoothing to limit over-confidence."""
        with tf.name_scope("smoothing_cross_entropy", [logits, labels]):
            # Low confidence is given to all non-true labels, uniformly.
            low_confidence = (1.0 - confidence) / tf.to_float(vocab_size - 1)
            # Normalizing constant is the best cross-entropy value with soft targets.
            # We subtract it just for readability, makes no difference on learning.
            normalizing = -(confidence * tf.log(confidence) + tf.to_float(vocab_size - 1) * low_confidence * tf.log(low_confidence + 1e-20))
            # Soft targets.
            soft_targets = tf.one_hot(
                tf.cast(labels, tf.int32),
                depth=vocab_size,
                on_value=confidence,
                off_value=low_confidence)
            xentropy = tf.nn.softmax_cross_entropy_with_logits(
                logits=logits, labels=soft_targets)
        return xentropy - normalizing

def smoothing_cross_entropy(self,logits, labels, vocab_size, confidence=0.9): #confidence = 1.0 - label_smoothing. where label_smooth=0.1. from http://github.com/tensorflow/tensor2tensor
        """Cross entropy with label smoothing to limit over-confidence."""
        with tf.name_scope("smoothing_cross_entropy", [logits, labels]):
            # Low confidence is given to all non-true labels, uniformly.
            low_confidence = (1.0 - confidence) / tf.to_float(vocab_size - 1)
            # Normalizing constant is the best cross-entropy value with soft targets.
            # We subtract it just for readability, makes no difference on learning.
            normalizing = -(confidence * tf.log(confidence) + tf.to_float(vocab_size - 1) * low_confidence * tf.log(low_confidence + 1e-20))
            # Soft targets.
            soft_targets = tf.one_hot(
                tf.cast(labels, tf.int32),
                depth=vocab_size,
                on_value=confidence,
                off_value=low_confidence)
            xentropy = tf.nn.softmax_cross_entropy_with_logits(
                logits=logits, labels=soft_targets)
        return xentropy - normalizing

def build_loss(self, inp, output):
        y_gt = inp['y_gt']
        y_out = output['y_out']
        ce = tfplus.nn.CE()({'y_gt': y_gt, 'y_out': y_out})
        num_ex_f = tf.to_float(tf.shape(inp['x'])[0])
        ce = tf.reduce_sum(ce) / num_ex_f
        self.add_loss(ce)
        total_loss = self.get_loss()
        self.register_var('loss', total_loss)

        ans = tf.argmax(y_gt, 1)
        correct = tf.equal(ans, tf.argmax(y_out, 1))
        top5_acc = tf.reduce_sum(tf.to_float(
            tf.nn.in_top_k(y_out, ans, 5))) / num_ex_f
        self.register_var('top5_acc', top5_acc)
        acc = tf.reduce_sum(tf.to_float(correct)) / num_ex_f
        self.register_var('acc', acc)
        return total_loss

def _score(self, prev_decoder_state, prev_embedding):
        # Returns scores in a tensor of shape [batch_size, input_sequence_length]

        if self.mode == 'decode':
            query_part = self.query_attention_partial_score_placeholder
            encoder_part = self.encoder_state_attention_partial_scores_placeholder
        else:
            query_part = self.query_attention_partial_score
            encoder_part = self.encoder_state_attention_partial_scores

        embedding_part = tf.matmul(prev_embedding, self.attention_w_e)

        output = tf.matmul(prev_decoder_state,
                           self.attention_w) + embedding_part + query_part + encoder_part + self.attention_b
        output = tf.tanh(output)
        output = tf.reduce_sum(self.attention_v * output, axis=2)
        output = tf.transpose(output, [1, 0])

        # Handle input document padding by giving a large penalty, eliminating it from the weighted average
        padding_penalty = -1e20 * tf.to_float(1 - tf.sign(self.documents_placeholder))
        masked = output + padding_penalty

        return masked

def cyclic_learning_rate(
        learning_rate_min,
        learning_rate_max,
        step_size,
        global_step,
        mode='triangular',
        scope=None):
    with tf.variable_scope(scope, 'CyclicLearningRate'):
        cycle = tf.floor(1 + tf.to_float(global_step) / (2 * step_size))

        if mode == 'triangular':
            scale = 1
        elif mode == 'triangular2':
            scale = 2**(cycle - 1)
        else:
            raise ValueError('Unrecognized mode: {}'.format(mode))

        x = tf.abs(tf.to_float(global_step) / step_size - 2 * cycle + 1)
        lr = learning_rate_min + (learning_rate_max - learning_rate_min) * \
            tf.maximum(0.0, 1 - x) / scale

        return lr

def ar_layer(z0,hps,n_hidden=10):
    ''' old iaf layer '''
    # Repeat input
    z_rep = tf.reshape(tf.tile(z0,[1,hps.z_size]),[-1,hps.z_size])

    # make mask    
    mask = tf.sequence_mask(tf.range(hps.z_size),hps.z_size)[None,:,:]
    mask = tf.reshape(tf.tile(mask,[tf.shape(z0)[0],1,1]),[-1,hps.z_size])

    # predict mu and sigma
    z_mask = z_rep * tf.to_float(mask)
    mid = slim.fully_connected(z_mask,n_hidden,activation_fn=tf.nn.relu)
    pars = slim.fully_connected(mid,2,activation_fn=None)
    pars = tf.reshape(pars,[-1,hps.z_size,2])    
    mu, log_sigma = tf.unstack(pars,axis=2)
    return mu, log_sigma

def shrink_soft_threshold(r,rvar,theta):
    """
    soft threshold function
        y=sign(x)*max(0,abs(x)-theta[0]*sqrt(rvar) )*scaling
    where scaling is theta[1] (default=1)
    in other words, if theta is len(1), then the standard
    """
    if len(theta.get_shape())>0 and theta.get_shape() != (1,):
        lam = theta[0] * tf.sqrt(rvar)
        scale=theta[1]
    else:
        lam  = theta * tf.sqrt(rvar)
        scale = None
    lam = tf.maximum(lam,0)
    arml = tf.abs(r) - lam
    xhat = tf.sign(r) * tf.maximum(arml,0)
    dxdr = tf.reduce_mean(tf.to_float(arml>0),0)
    if scale is not None:
        xhat = xhat*scale
        dxdr = dxdr*scale
    return (xhat,dxdr)

def shrink_spline(r,rvar,theta):
    """ Spline-based shrinkage function
    """
    scale = theta[0]*tf.sqrt(rvar)
    rs = tf.sign(r)
    ar = tf.abs(r/scale)
    ar2 = tf.square(ar)
    ar3 = ar*ar2
    reg1 = tf.to_float(ar<1)
    reg2 = tf.to_float(ar<2)-reg1
    ar_m2 = 2-ar
    ar_m2_p2 = tf.square(ar_m2)
    ar_m2_p3 = ar_m2*ar_m2_p2
    beta3 = ( (2./3 - ar2  + .5*ar3)*reg1 + (1./6*(ar_m2_p3))*reg2 )
    xhat = r*(theta[1] + theta[2]*beta3)
    return (xhat,auto_gradients(xhat,r))

def _embed_sentences(self):
        """Tensorflow implementation of Simple but Tough-to-Beat Baseline"""
        # Get word features
        word_embeddings = self._get_embedding()
        word_feats      = tf.nn.embedding_lookup(word_embeddings, self.input)
        # Get marginal estimates and scaling term
        batch_size = tf.shape(word_feats)[0]
        a = tf.pow(10.0, self._get_a_exp())
        p = tf.constant(self.marginals, dtype=tf.float32, name='marginals')
        q = tf.reshape(
            a / (a + tf.nn.embedding_lookup(p, self.input)),
            (batch_size, self.mx_len, 1)
        )
        # Compute initial sentence embedding
        z = tf.reshape(1.0 / tf.to_float(self.input_lengths), (batch_size, 1))
        S = z * tf.reduce_sum(q * word_feats, axis=1)
        # Compute common component
        S_centered = S - tf.reduce_mean(S, axis=0)
        _, _, V = tf.svd(S_centered, full_matrices=False, compute_uv=True)
        self.tf_ccx = tf.stop_gradient(tf.gather(tf.transpose(V), 0))
        # Common component removal
        ccx = tf.reshape(self._get_common_component(), (1, self.d))
        sv = {'embeddings': word_embeddings, 'a': a, 'p': p, 'ccx': ccx}
        return S - tf.matmul(S, ccx * tf.transpose(ccx)), sv

def rickerWavelet(scale, sampleCount):
    def waveEquation(time): 
        time = tf.to_float(time)

        tSquare = time ** 2.
        sigma   = 1.
        sSquare = sigma ** 2.

        # _1 = 2 / ((3 * a) ** .5 * np.pi ** .25)
        _1a = (3. * sigma) ** .5
        _1b = np.pi ** .25
        _1 = 2. / (_1a * _1b)

        # _2 = 1 - t**2 / a**2
        _2 = 1. - tSquare / sSquare

        # _3 = np.exp(-(t**2) / (2 * a ** 2))
        _3a = -1. * tSquare
        _3b = 2. * sSquare
        _3 = tf.exp(_3a / _3b)

        return _1 * _2 * _3

    return waveletHelper(scale, sampleCount, waveEquation)

def process_image(img, scale, isotropic, crop, mean):
    '''Crops, scales, and normalizes the given image.
    scale : The image wil be first scaled to this size.
            If isotropic is true, the smaller side is rescaled to this,
            preserving the aspect ratio.
    crop  : After scaling, a central crop of this size is taken.
    mean  : Subtracted from the image
    '''
    # Rescale
    if isotropic:
        img_shape = tf.to_float(tf.shape(img)[:2])
        min_length = tf.minimum(img_shape[0], img_shape[1])
        new_shape = tf.to_int32((scale / min_length) * img_shape)
    else:
        new_shape = tf.pack([scale, scale])
    img = tf.image.resize_images(img, new_shape[0], new_shape[1])
    # Center crop
    # Use the slice workaround until crop_to_bounding_box supports deferred tensor shapes
    # See: https://github.com/tensorflow/tensorflow/issues/521
    offset = (new_shape - crop) / 2
    img = tf.slice(img, begin=tf.pack([offset[0], offset[1], 0]), size=tf.pack([crop, crop, -1]))
    # Mean subtraction
    return tf.to_float(img) - mean

def create_test_input(batch_size, height, width, channels):
  """Create test input tensor.

  Args:
    batch_size: The number of images per batch or `None` if unknown.
    height: The height of each image or `None` if unknown.
    width: The width of each image or `None` if unknown.
    channels: The number of channels per image or `None` if unknown.

  Returns:
    Either a placeholder `Tensor` of dimension
      [batch_size, height, width, channels] if any of the inputs are `None` or a
    constant `Tensor` with the mesh grid values along the spatial dimensions.
  """
  if None in [batch_size, height, width, channels]:
    return tf.placeholder(tf.float32, (batch_size, height, width, channels))
  else:
    return tf.to_float(
        np.tile(
            np.reshape(
                np.reshape(np.arange(height), [height, 1]) +
                np.reshape(np.arange(width), [1, width]),
                [1, height, width, 1]),
            [batch_size, 1, 1, channels]))

def create_test_input(batch_size, height, width, channels):
  """Create test input tensor.

  Args:
    batch_size: The number of images per batch or `None` if unknown.
    height: The height of each image or `None` if unknown.
    width: The width of each image or `None` if unknown.
    channels: The number of channels per image or `None` if unknown.

  Returns:
    Either a placeholder `Tensor` of dimension
      [batch_size, height, width, channels] if any of the inputs are `None` or a
    constant `Tensor` with the mesh grid values along the spatial dimensions.
  """
  if None in [batch_size, height, width, channels]:
    return tf.placeholder(tf.float32, (batch_size, height, width, channels))
  else:
    return tf.to_float(
        np.tile(
            np.reshape(
                np.reshape(np.arange(height), [height, 1]) +
                np.reshape(np.arange(width), [1, width]),
                [1, height, width, 1]),
            [batch_size, 1, 1, channels]))

def preprocess_for_eval(image, output_height, output_width, resize_side):
  """Preprocesses the given image for evaluation.

  Args:
    image: A `Tensor` representing an image of arbitrary size.
    output_height: The height of the image after preprocessing.
    output_width: The width of the image after preprocessing.
    resize_side: The smallest side of the image for aspect-preserving resizing.

  Returns:
    A preprocessed image.
  """
  image = _aspect_preserving_resize(image, resize_side)
  image = _central_crop([image], output_height, output_width)[0]
  image.set_shape([output_height, output_width, 3])
  image = tf.to_float(image)
  return _mean_image_subtraction(image, [_R_MEAN, _G_MEAN, _B_MEAN])

def extract_batch(dataset, config):
    with tf.device("/cpu:0"):
        bboxer = PriorBoxGrid(config)
        data_provider = slim.dataset_data_provider.DatasetDataProvider(
            dataset, num_readers=2,
            common_queue_capacity=512, common_queue_min=32)
        if args.segment:
            im, bbox, gt, seg = data_provider.get(['image', 'object/bbox', 'object/label',
                                                   'image/segmentation'])
        else:
            im, bbox, gt = data_provider.get(['image', 'object/bbox', 'object/label'])
            seg = tf.expand_dims(tf.zeros(tf.shape(im)[:2]), 2)
        im = tf.to_float(im)/255
        bbox = yxyx_to_xywh(tf.clip_by_value(bbox, 0.0, 1.0))

        im, bbox, gt, seg = data_augmentation(im, bbox, gt, seg, config)
        inds, cats, refine = bboxer.encode_gt_tf(bbox, gt)

        return tf.train.shuffle_batch([im, inds, refine, cats, seg],
                                      args.batch_size, 2048, 64, num_threads=4)

def zoomout(image, gt_bboxes, params):
    X_out = tf.random_uniform([], 1.05, params['X_out'])
    h, w, _ = tf.unstack(tf.to_float(tf.shape(image)))
    zoomout_color = params['zoomout_color']+[0]

    bg_color = tf.constant(zoomout_color, dtype=tf.float32)
    x_shift = tf.random_uniform([], 0, (X_out - 1) * w)
    y_shift = tf.random_uniform([], 0, (X_out - 1) * h)
    x2_shift = (X_out - 1) * w - x_shift
    y2_shift = (X_out - 1) * h - y_shift
    # somewhat hacky solution to pad with MEAN_COLOR
    # tf.pad does not support custom constant padding unlike numpy
    image -= bg_color
    image = tf.pad(image, tf.to_int32([[y_shift, y2_shift], [x_shift, x2_shift], [0, 0]]))
    image += bg_color

    gt_x, gt_y, gt_w, gt_h = tf.unstack(gt_bboxes, axis=1)
    gt_bboxes = tf.stack([gt_x + x_shift/w,
                          gt_y + y_shift/h,
                          gt_w, gt_h], axis=1)/X_out
    return image, gt_bboxes

def __init__(self, epsilon=1e-2, shape=()):

        self._sum = tf.get_variable(
            dtype=tf.float64,
            shape=shape,
            initializer=tf.constant_initializer(0.0),
            name="runningsum", trainable=False)
        self._sumsq = tf.get_variable(
            dtype=tf.float64,
            shape=shape,
            initializer=tf.constant_initializer(epsilon),
            name="runningsumsq", trainable=False)
        self._count = tf.get_variable(
            dtype=tf.float64,
            shape=(),
            initializer=tf.constant_initializer(epsilon),
            name="count", trainable=False)
        self.shape = shape

        self.mean = tf.to_float(self._sum / self._count)
        self.std = tf.sqrt( tf.maximum( tf.to_float(self._sumsq / self._count) - tf.square(self.mean) , 1e-2 ))

        newsum = tf.placeholder(shape=self.shape, dtype=tf.float64, name='sum')
        newsumsq = tf.placeholder(shape=self.shape, dtype=tf.float64, name='var')
        newcount = tf.placeholder(shape=[], dtype=tf.float64, name='count')
        self.incfiltparams = U.function([newsum, newsumsq, newcount], [],
            updates=[tf.assign_add(self._sum, newsum),
                     tf.assign_add(self._sumsq, newsumsq),
                     tf.assign_add(self._count, newcount)])

def load_image(image_file, image_size=None):
  """Loads an image and center-crops it to a specific size.

  Args:
    image_file: str. Image file.
    image_size: int, optional. Desired size. If provided, crops the image to
        a square and resizes it to the requested size. Defaults to None.

  Returns:
    A 4-D tensor of shape [1, image_size, image_size, 3] and dtype float32,
    with values in [0, 1].
  """
  image = tf.constant(np.uint8(load_np_image(image_file) * 255.0))
  if image_size is not None:
    # Center-crop into a square and resize to image_size
    small_side = min(image.get_shape()[0].value, image.get_shape()[1].value)
    image = tf.image.resize_image_with_crop_or_pad(
        image, small_side, small_side)
    image = tf.image.resize_images(image, [image_size, image_size])
  image = tf.to_float(image) / 255.0

  return tf.expand_dims(image, 0)

def center_crop_resize_image(image, image_size):
  """Center-crop into a square and resize to image_size.

  Args:
    image: A 3-D image `Tensor`.
    image_size: int, Desired size. Crops the image to a square and resizes it
      to the requested size.

  Returns:
    A 4-D tensor of shape [1, image_size, image_size, 3] and dtype float32,
    with values in [0, 1].
  """
  shape = tf.shape(image)
  small_side = tf.minimum(shape[0], shape[1])
  image = tf.image.resize_image_with_crop_or_pad(image, small_side, small_side)
  image = tf.to_float(image) / 255.0

  image = tf.image.resize_images(image, tf.constant([image_size, image_size]))

  return tf.expand_dims(image, 0)

def encode(self, sequence, sequence_length):
    """Encodes input sequences into a MultivariateNormalDiag distribution."""
    hparams = self.hparams
    z_size = hparams.z_size

    sequence = tf.to_float(sequence)
    encoder_output = self.encoder.encode(sequence, sequence_length)

    mu = tf.layers.dense(
        encoder_output,
        z_size,
        name='encoder/mu',
        kernel_initializer=tf.random_normal_initializer(stddev=0.001))
    sigma = tf.layers.dense(
        encoder_output,
        z_size,
        activation=tf.nn.softplus,
        name='encoder/sigma',
        kernel_initializer=tf.random_normal_initializer(stddev=0.001))

    return ds.MultivariateNormalDiag(loc=mu, scale_diag=sigma)