Python backend.sum方法代码示例

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def call(self, inputs):
    """
    parent layers: atom_features, distance, distance_membership_i, distance_membership_j
    """
    atom_features = inputs[0]
    distance = inputs[1]
    distance_membership_i = inputs[2]
    distance_membership_j = inputs[3]
    distance_hidden = tf.matmul(distance, self.W_df) + self.b_df
    atom_features_hidden = tf.matmul(atom_features, self.W_cf) + self.b_cf
    outputs = tf.multiply(
        distance_hidden, tf.gather(atom_features_hidden, distance_membership_j))

    # for atom i in a molecule m, this step multiplies together distance info of atom pair(i,j)
    # and embeddings of atom j(both gone through a hidden layer)
    outputs = tf.matmul(outputs, self.W_fc)
    outputs = self.activation_fn(outputs)

    output_ii = tf.multiply(self.b_df, atom_features_hidden)
    output_ii = tf.matmul(output_ii, self.W_fc)
    output_ii = self.activation_fn(output_ii)

    # for atom i, sum the influence from all other atom j in the molecule
    return tf.math.segment_sum(
        outputs, distance_membership_i) - output_ii + atom_features 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def call(self, inputs):
        if self.data_mode == 'disjoint':
            X, I = inputs
            if K.ndim(I) == 2:
                I = I[:, 0]
        else:
            X = inputs
        inputs_linear = self.features_layer(X)
        attn = self.attention_layer(X)
        masked_inputs = inputs_linear * attn
        if self.data_mode in {'single', 'batch'}:
            output = K.sum(masked_inputs, axis=-2,
                           keepdims=self.data_mode == 'single')
        else:
            output = tf.math.segment_sum(masked_inputs, I)

        return output 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def loss(self, y_true, y_pred):

        # get the value for the true and fake images
        disc_true = self.disc(y_true)
        disc_pred = self.disc(y_pred)

        # sample a x_hat by sampling along the line between true and pred
        # z = tf.placeholder(tf.float32, shape=[None, 1])
        # shp = y_true.get_shape()[0]
        # WARNING: SHOULD REALLY BE shape=[batch_size, 1] !!!
        # self.batch_size does not work, since it's not None!!!
        alpha = K.random_uniform(shape=[K.shape(y_pred)[0], 1, 1, 1])
        diff = y_pred - y_true
        interp = y_true + alpha * diff

        # take gradient of D(x_hat)
        gradients = K.gradients(self.disc(interp), [interp])[0]
        grad_pen = K.mean(K.square(K.sqrt(K.sum(K.square(gradients), axis=1))-1))

        # compute loss
        return (K.mean(disc_pred) - K.mean(disc_true)) + self.lambda_gp * grad_pen 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def focal_loss_binary(y_true, y_pred):
    """Binary cross-entropy focal loss
    """
    gamma = 2.0
    alpha = 0.25

    pt_1 = tf.where(tf.equal(y_true, 1),
                    y_pred,
                    tf.ones_like(y_pred))
    pt_0 = tf.where(tf.equal(y_true, 0),
                    y_pred,
                    tf.zeros_like(y_pred))

    epsilon = K.epsilon()
    # clip to prevent NaN and Inf
    pt_1 = K.clip(pt_1, epsilon, 1. - epsilon)
    pt_0 = K.clip(pt_0, epsilon, 1. - epsilon)

    weight = alpha * K.pow(1. - pt_1, gamma)
    fl1 = -K.sum(weight * K.log(pt_1))
    weight = (1 - alpha) * K.pow(pt_0, gamma)
    fl0 = -K.sum(weight * K.log(1. - pt_0))

    return fl1 + fl0 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def focal_loss_categorical(y_true, y_pred):
    """Categorical cross-entropy focal loss"""
    gamma = 2.0
    alpha = 0.25

    # scale to ensure sum of prob is 1.0
    y_pred /= K.sum(y_pred, axis=-1, keepdims=True)

    # clip the prediction value to prevent NaN and Inf
    epsilon = K.epsilon()
    y_pred = K.clip(y_pred, epsilon, 1. - epsilon)

    # calculate cross entropy
    cross_entropy = -y_true * K.log(y_pred)

    # calculate focal loss
    weight = alpha * K.pow(1 - y_pred, gamma)
    cross_entropy *= weight

    return K.sum(cross_entropy, axis=-1) 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def surv_likelihood(n_intervals):
  """Create custom Keras loss function for neural network survival model. 
  Arguments
      n_intervals: the number of survival time intervals
  Returns
      Custom loss function that can be used with Keras
  """
  def loss(y_true, y_pred):
    """
    Required to have only 2 arguments by Keras.
    Arguments
        y_true: Tensor.
          First half of the values is 1 if individual survived that interval, 0 if not.
          Second half of the values is for individuals who failed, and is 1 for time interval during which failure occured, 0 for other intervals.
          See make_surv_array function.
        y_pred: Tensor, predicted survival probability (1-hazard probability) for each time interval.
    Returns
        Vector of losses for this minibatch.
    """
    cens_uncens = 1. + y_true[:,0:n_intervals] * (y_pred-1.) #component for all individuals
    uncens = 1. - y_true[:,n_intervals:2*n_intervals] * y_pred #component for only uncensored individuals
    return K.sum(-K.log(K.clip(K.concatenate((cens_uncens,uncens)),K.epsilon(),None)),axis=-1) #return -log likelihood
  return loss 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def dice_soft(y_true, y_pred, smooth=0.00001):
    # Identify axis
    axis = identify_axis(y_true.get_shape())

    # Calculate required variables
    intersection = y_true * y_pred
    intersection = K.sum(intersection, axis=axis)
    y_true = K.sum(y_true, axis=axis)
    y_pred = K.sum(y_pred, axis=axis)

    # Calculate Soft Dice Similarity Coefficient
    dice = ((2 * intersection) + smooth) / (y_true + y_pred + smooth)

    # Obtain mean of Dice & return result score
    dice = K.mean(dice)
    return dice 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def dice_weighted(weights):
    weights = K.variable(weights)

    def weighted_loss(y_true, y_pred, smooth=0.00001):
        axis = identify_axis(y_true.get_shape())
        intersection = y_true * y_pred
        intersection = K.sum(intersection, axis=axis)
        y_true = K.sum(y_true, axis=axis)
        y_pred = K.sum(y_pred, axis=axis)
        dice = ((2 * intersection) + smooth) / (y_true + y_pred + smooth)
        dice = dice * weights
        return -dice
    return weighted_loss

#-----------------------------------------------------#
#              Dice & Crossentropy loss               #
#-----------------------------------------------------# 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def dice_crossentropy(y_truth, y_pred):
    # Obtain Soft DSC
    dice = dice_soft_loss(y_truth, y_pred)
    # Obtain Crossentropy
    crossentropy = K.categorical_crossentropy(y_truth, y_pred)
    crossentropy = K.mean(crossentropy)
    # Return sum
    return dice + crossentropy

#-----------------------------------------------------#
#                    Tversky loss                     #
#-----------------------------------------------------#
#                     Reference:                      #
#                Sadegh et al. (2017)                 #
#     Tversky loss function for image segmentation    #
#      using 3D fully convolutional deep networks     #
#-----------------------------------------------------#
# alpha=beta=0.5 : dice coefficient                   #
# alpha=beta=1   : jaccard                            #
# alpha+beta=1   : produces set of F*-scores          #
#-----------------------------------------------------# 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def tversky_loss(y_true, y_pred, smooth=0.000001):
    # Define alpha and beta
    alpha = 0.5
    beta  = 0.5
    # Calculate Tversky for each class
    axis = identify_axis(y_true.get_shape())
    tp = K.sum(y_true * y_pred, axis=axis)
    fn = K.sum(y_true * (1-y_pred), axis=axis)
    fp = K.sum((1-y_true) * y_pred, axis=axis)
    tversky_class = (tp + smooth)/(tp + alpha*fn + beta*fp + smooth)
    # Sum up classes to one score
    tversky = K.sum(tversky_class, axis=[-1])
    # Identify number of classes
    n = K.cast(K.shape(y_true)[-1], 'float32')
    # Return Tversky
    return n-tversky

#-----------------------------------------------------#
#             Tversky & Crossentropy loss             #
#-----------------------------------------------------# 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def mcor(y_true, y_pred):
    # matthews_correlation
    y_pred_pos = K.round(K.clip(y_pred, 0, 1))
    y_pred_neg = 1 - y_pred_pos

    y_pos = K.round(K.clip(y_true, 0, 1))
    y_neg = 1 - y_pos

    tp = K.sum(y_pos * y_pred_pos)
    tn = K.sum(y_neg * y_pred_neg)

    fp = K.sum(y_neg * y_pred_pos)
    fn = K.sum(y_pos * y_pred_neg)

    numerator = (tp * tn - fp * fn)
    denominator = K.sqrt((tp + fp) * (tp + fn) * (tn + fp) * (tn + fn))

    return numerator / (denominator + K.epsilon()) 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def mcor(y_true, y_pred):
    # Matthews correlation
    y_pred_pos = K.round(K.clip(y_pred, 0, 1))
    y_pred_neg = 1 - y_pred_pos

    y_pos = K.round(K.clip(y_true, 0, 1))
    y_neg = 1 - y_pos

    tp = K.sum(y_pos * y_pred_pos)
    tn = K.sum(y_neg * y_pred_neg)

    fp = K.sum(y_neg * y_pred_pos)
    fn = K.sum(y_pos * y_pred_neg)

    numerator = (tp * tn - fp * fn)
    denominator = K.sqrt((tp + fp) * (tp + fn) * (tn + fp) * (tn + fn))

    return numerator / (denominator + K.epsilon()) 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def recall(y_true, y_pred):
    """Precision for foreground pixels.

    Calculates pixelwise recall TP/(TP + FN).

    """
    # count true positives
    truth = K.round(K.clip(y_true, K.epsilon(), 1))
    pred_pos = K.round(K.clip(y_pred, K.epsilon(), 1))
    true_pos = K.sum(K.cast(K.all(K.stack([truth, pred_pos], axis=2), axis=2),
                            dtype='float64'))
    truth_ct = K.sum(K.round(K.clip(y_true, K.epsilon(), 1)))
    if truth_ct == 0:
        return 0
    recall = true_pos/truth_ct

    return recall 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def _cosine_dist(x, y):
  """Computes the inner product (cosine distance) between two tensors.

  Parameters
  ----------
  x: tf.Tensor
    Input Tensor
  y: tf.Tensor
    Input Tensor
  """
  denom = (backend.sqrt(backend.sum(tf.square(x)) * backend.sum(tf.square(y))) +
           backend.epsilon())
  return backend.dot(x, tf.transpose(y)) / denom 

# 需要导入模块: from tensorflow.keras import backend [as 别名]
# 或者: from tensorflow.keras.backend import sum [as 别名]
def gradient_penalty(samples, output, weight):
    gradients = K.gradients(output, samples)[0]
    gradients_sqr = K.square(gradients)
    gradient_penalty = K.sum(gradients_sqr,
                              axis=np.arange(1, len(gradients_sqr.shape)))

    # (weight / 2) * ||grad||^2
    # Penalize the gradient norm
    return K.mean(gradient_penalty) * weight