#! /usr/bin/python
# -*- coding: utf8 -*-
import tensorflow as tf
import numbers
from tensorflow.python.framework import ops
from tensorflow.python.ops import standard_ops
## Cost Functions
[docs]def cross_entropy(output, target, name="cross_entropy_loss"):
"""Returns the TensorFlow expression of cross-entropy of two distributions, implement
softmax internally.
Parameters
----------
output : Tensorflow variable
A distribution with shape: [batch_size, n_feature].
target : Tensorflow variable
A distribution with shape: [batch_size, n_feature].
Examples
--------
>>> ce = tf.cost.cross_entropy(y_logits, y_target_logits)
References
-----------
- About cross-entropy: `wiki <https://en.wikipedia.org/wiki/Cross_entropy>`_.\n
- The code is borrowed from: `here <https://en.wikipedia.org/wiki/Cross_entropy>`_.
"""
with tf.name_scope(name):
# net_output_tf = output
# target_tf = target
# cross_entropy = tf.add(tf.mul(tf.log(net_output_tf, name=None),target_tf),
# tf.mul(tf.log(1 - net_output_tf), (1 - target_tf)))
# return -1 * tf.reduce_mean(tf.reduce_sum(cross_entropy, 1), name='cross_entropy_mean')
return tf.reduce_mean(tf.nn.sparse_softmax_cross_entropy_with_logits(output, target))
[docs]def binary_cross_entropy(output, target, epsilon=1e-8, name='bce_loss'):
"""Computes binary cross entropy given `output`.
For brevity, let `x = `, `z = targets`. The logistic loss is
loss(x, z) = - sum_i (x[i] * log(z[i]) + (1 - x[i]) * log(1 - z[i]))
Parameters
----------
output : tensor of type `float32` or `float64`.
target : tensor of the same type and shape as `output`.
epsilon : float
A small value to avoid output is zero.
name : string
An optional name to attach to this layer.
References
-----------
- `DRAW <https://github.com/ericjang/draw/blob/master/draw.py#L73>`_
"""
# from tensorflow.python.framework import ops
# with ops.op_scope([output, target], name, "bce_loss") as name:
# output = ops.convert_to_tensor(output, name="preds")
# target = ops.convert_to_tensor(targets, name="target")
with tf.name_scope(name):
return tf.reduce_mean(-(target * tf.log(output + epsilon) +
(1. - target) * tf.log(1. - output + epsilon)))
[docs]def mean_squared_error(output, target):
"""Return the TensorFlow expression of mean-squre-error of two distributions.
Parameters
----------
output : tensorflow variable
A distribution with shape: [batch_size, n_feature].
target : tensorflow variable
A distribution with shape: [batch_size, n_feature].
"""
with tf.name_scope("mean_squared_error_loss"):
mse = tf.reduce_sum(tf.squared_difference(output, target), reduction_indices = 1)
return tf.reduce_mean(mse)
[docs]def dice_coe(output, target, epsilon=1e-10):
"""Sørensen–Dice coefficient for comparing the similarity of two distributions,
usually be used for binary image segmentation i.e. labels are binary.
The coefficient = [0, 1], 1 if totally match.
Parameters
-----------
output : tensor
A distribution with shape: [batch_size, ....], (any dimensions).
target : tensor
A distribution with shape: [batch_size, ....], (any dimensions).
epsilon : float
An optional name to attach to this layer.
Examples
---------
>>> outputs = tl.act.pixel_wise_softmax(network.outputs)
>>> dice_loss = 1 - tl.cost.dice_coe(outputs, y_, epsilon=1e-5)
References
-----------
- `wiki-dice <https://en.wikipedia.org/wiki/Sørensen–Dice_coefficient>`_
"""
# inse = tf.reduce_sum( tf.mul(output, target) )
# l = tf.reduce_sum( tf.mul(output, output) )
# r = tf.reduce_sum( tf.mul(target, target) )
inse = tf.reduce_sum( output * target )
l = tf.reduce_sum( output * output )
r = tf.reduce_sum( target * target )
dice = 2 * (inse) / (l + r)
if epsilon == 0:
return dice
else:
return tf.clip_by_value(dice, 0, 1.0-epsilon)
[docs]def iou_coe(output, target, threshold=0.5, epsilon=1e-10):
"""Intersection over Union (Hard Dice), usually be used for evaluating binary image segmentation.
The coefficient = [0, 1], 1 means totally match.
Parameters
-----------
output : tensor
A distribution with shape: [batch_size, ....], (any dimensions).
target : tensor
A distribution with shape: [batch_size, ....], (any dimensions).
threshold : float
The threshold value to be true.
epsilon : float
A small value to avoid zero denominator when both output and target output nothing.
Examples
---------
>>> outputs = tl.act.pixel_wise_softmax(network.outputs)
>>> iou = tl.cost.iou_coe(outputs[:,:,:,0], y_[:,:,:,0])
Notes
------
- IOU cannot be used as training loss, people usually use dice coefficient for training, and IOU for evaluating.
"""
pre = tf.cast(output > threshold, dtype=tf.float32)
truth = tf.cast(target > threshold, dtype=tf.float32)
intersection = tf.reduce_sum(pre * truth)
union = tf.reduce_sum(tf.cast((pre + truth) > threshold, dtype=tf.float32))
return tf.reduce_sum(intersection) / (tf.reduce_sum(union) + epsilon)
[docs]def cross_entropy_seq(logits, target_seqs, batch_size=1, num_steps=None):
"""Returns the expression of cross-entropy of two sequences, implement
softmax internally. Normally be used for Fixed Length RNN outputs.
Parameters
----------
logits : Tensorflow variable
2D tensor, ``network.outputs``, [batch_size*n_steps (n_examples), number of output units]
target_seqs : Tensorflow variable
target : 2D tensor [batch_size, n_steps], if the number of step is dynamic, please use ``cross_entropy_seq_with_mask`` instead.
batch_size : a int, default is 1
RNN batch_size, number of concurrent processes, divide the loss by batch_size.
num_steps : a int
sequence length
Examples
--------
>>> see PTB tutorial for more details
>>> input_data = tf.placeholder(tf.int32, [batch_size, num_steps])
>>> targets = tf.placeholder(tf.int32, [batch_size, num_steps])
>>> cost = tf.cost.cross_entropy_seq(network.outputs, targets, batch_size, num_steps)
"""
loss = tf.nn.seq2seq.sequence_loss_by_example(
[logits],
[tf.reshape(target_seqs, [-1])],
[tf.ones([batch_size * num_steps])])
cost = tf.reduce_sum(loss) / batch_size
return cost
[docs]def cross_entropy_seq_with_mask(logits, target_seqs, input_mask, return_details=False):
"""Returns the expression of cross-entropy of two sequences, implement
softmax internally. Normally be used for Dynamic RNN outputs.
Parameters
-----------
logits : network identity outputs
2D tensor, ``network.outputs``, [batch_size, number of output units].
target_seqs : int of tensor, like word ID.
[batch_size, ?]
input_mask : the mask to compute loss
The same size with target_seqs, normally 0 and 1.
return_details : boolean
- If False (default), only returns the loss.
- If True, returns the loss, losses, weights and targets (reshape to one vetcor).
Examples
--------
- see Image Captioning Example.
"""
targets = tf.reshape(target_seqs, [-1]) # to one vector
weights = tf.to_float(tf.reshape(input_mask, [-1])) # to one vector like targets
losses = tf.nn.sparse_softmax_cross_entropy_with_logits(logits, targets)
loss = tf.div(tf.reduce_sum(tf.mul(losses, weights)), # loss from mask. reduce_sum before element-wise mul with mask !!
tf.reduce_sum(weights),
name="seq_loss_with_mask")
if return_details:
return loss, losses, weights, targets
else:
return loss
## Regularization Functions
[docs]def li_regularizer(scale):
"""li regularization removes the neurons of previous layer, `i` represents `inputs`.\n
Returns a function that can be used to apply group li regularization to weights.\n
The implementation follows `TensorFlow contrib <https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/layers/python/layers/regularizers.py>`_.
Parameters
----------
scale : float
A scalar multiplier `Tensor`. 0.0 disables the regularizer.
Returns
--------
A function with signature `li(weights, name=None)` that apply L1 regularization.
Raises
------
ValueError : if scale is outside of the range [0.0, 1.0] or if scale is not a float.
"""
import numbers
from tensorflow.python.framework import ops
from tensorflow.python.ops import standard_ops
# from tensorflow.python.platform import tf_logging as logging
if isinstance(scale, numbers.Integral):
raise ValueError('scale cannot be an integer: %s' % scale)
if isinstance(scale, numbers.Real):
if scale < 0.:
raise ValueError('Setting a scale less than 0 on a regularizer: %g' %
scale)
if scale >= 1.:
raise ValueError('Setting a scale greater than 1 on a regularizer: %g' %
scale)
if scale == 0.:
logging.info('Scale of 0 disables regularizer.')
return lambda _, name=None: None
def li(weights, name=None):
"""Applies li regularization to weights."""
with ops.op_scope([weights], name, 'li_regularizer') as scope:
my_scale = ops.convert_to_tensor(scale,
dtype=weights.dtype.base_dtype,
name='scale')
return standard_ops.mul(
my_scale,
standard_ops.reduce_sum(standard_ops.sqrt(standard_ops.reduce_sum(tf.square(weights), 1))),
name=scope)
return li
[docs]def lo_regularizer(scale):
"""lo regularization removes the neurons of current layer, `o` represents `outputs`\n
Returns a function that can be used to apply group lo regularization to weights.\n
The implementation follows `TensorFlow contrib <https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/layers/python/layers/regularizers.py>`_.
Parameters
----------
scale : float
A scalar multiplier `Tensor`. 0.0 disables the regularizer.
Returns
-------
A function with signature `lo(weights, name=None)` that apply Lo regularization.
Raises
------
ValueError : If scale is outside of the range [0.0, 1.0] or if scale is not a float.
"""
import numbers
from tensorflow.python.framework import ops
from tensorflow.python.ops import standard_ops
# from tensorflow.python.platform import tf_logging as logging
if isinstance(scale, numbers.Integral):
raise ValueError('scale cannot be an integer: %s' % scale)
if isinstance(scale, numbers.Real):
if scale < 0.:
raise ValueError('Setting a scale less than 0 on a regularizer: %g' %
scale)
if scale >= 1.:
raise ValueError('Setting a scale greater than 1 on a regularizer: %g' %
scale)
if scale == 0.:
logging.info('Scale of 0 disables regularizer.')
return lambda _, name=None: None
def lo(weights, name=None):
"""Applies group column regularization to weights."""
with ops.op_scope([weights], name, 'lo_regularizer') as scope:
my_scale = ops.convert_to_tensor(scale,
dtype=weights.dtype.base_dtype,
name='scale')
return standard_ops.mul(
my_scale,
standard_ops.reduce_sum(standard_ops.sqrt(standard_ops.reduce_sum(tf.square(weights), 0))),
name=scope)
return lo
[docs]def maxnorm_regularizer(scale=1.0):
"""Max-norm regularization returns a function that can be used
to apply max-norm regularization to weights.
About max-norm: `wiki <https://en.wikipedia.org/wiki/Matrix_norm#Max_norm>`_.\n
The implementation follows `TensorFlow contrib <https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/layers/python/layers/regularizers.py>`_.
Parameters
----------
scale : float
A scalar multiplier `Tensor`. 0.0 disables the regularizer.
Returns
---------
A function with signature `mn(weights, name=None)` that apply Lo regularization.
Raises
--------
ValueError : If scale is outside of the range [0.0, 1.0] or if scale is not a float.
"""
import numbers
from tensorflow.python.framework import ops
from tensorflow.python.ops import standard_ops
if isinstance(scale, numbers.Integral):
raise ValueError('scale cannot be an integer: %s' % scale)
if isinstance(scale, numbers.Real):
if scale < 0.:
raise ValueError('Setting a scale less than 0 on a regularizer: %g' %
scale)
# if scale >= 1.:
# raise ValueError('Setting a scale greater than 1 on a regularizer: %g' %
# scale)
if scale == 0.:
logging.info('Scale of 0 disables regularizer.')
return lambda _, name=None: None
def mn(weights, name=None):
"""Applies max-norm regularization to weights."""
with ops.op_scope([weights], name, 'maxnorm_regularizer') as scope:
my_scale = ops.convert_to_tensor(scale,
dtype=weights.dtype.base_dtype,
name='scale')
return standard_ops.mul(my_scale, standard_ops.reduce_max(standard_ops.abs(weights)), name=scope)
return mn
[docs]def maxnorm_o_regularizer(scale):
"""Max-norm output regularization removes the neurons of current layer.\n
Returns a function that can be used to apply max-norm regularization to each column of weight matrix.\n
The implementation follows `TensorFlow contrib <https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/layers/python/layers/regularizers.py>`_.
Parameters
----------
scale : float
A scalar multiplier `Tensor`. 0.0 disables the regularizer.
Returns
---------
A function with signature `mn_o(weights, name=None)` that apply Lo regularization.
Raises
---------
ValueError : If scale is outside of the range [0.0, 1.0] or if scale is not a float.
"""
import numbers
from tensorflow.python.framework import ops
from tensorflow.python.ops import standard_ops
if isinstance(scale, numbers.Integral):
raise ValueError('scale cannot be an integer: %s' % scale)
if isinstance(scale, numbers.Real):
if scale < 0.:
raise ValueError('Setting a scale less than 0 on a regularizer: %g' %
scale)
# if scale >= 1.:
# raise ValueError('Setting a scale greater than 1 on a regularizer: %g' %
# scale)
if scale == 0.:
logging.info('Scale of 0 disables regularizer.')
return lambda _, name=None: None
def mn_o(weights, name=None):
"""Applies max-norm regularization to weights."""
with ops.op_scope([weights], name, 'maxnorm_o_regularizer') as scope:
my_scale = ops.convert_to_tensor(scale,
dtype=weights.dtype.base_dtype,
name='scale')
return standard_ops.mul(my_scale, standard_ops.reduce_sum(standard_ops.reduce_max(standard_ops.abs(weights), 0)), name=scope)
return mn_o
[docs]def maxnorm_i_regularizer(scale):
"""Max-norm input regularization removes the neurons of previous layer.\n
Returns a function that can be used to apply max-norm regularization to each row of weight matrix.\n
The implementation follows `TensorFlow contrib <https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/layers/python/layers/regularizers.py>`_.
Parameters
----------
scale : float
A scalar multiplier `Tensor`. 0.0 disables the regularizer.
Returns
---------
A function with signature `mn_i(weights, name=None)` that apply Lo regularization.
Raises
---------
ValueError : If scale is outside of the range [0.0, 1.0] or if scale is not a float.
"""
import numbers
from tensorflow.python.framework import ops
from tensorflow.python.ops import standard_ops
if isinstance(scale, numbers.Integral):
raise ValueError('scale cannot be an integer: %s' % scale)
if isinstance(scale, numbers.Real):
if scale < 0.:
raise ValueError('Setting a scale less than 0 on a regularizer: %g' %
scale)
# if scale >= 1.:
# raise ValueError('Setting a scale greater than 1 on a regularizer: %g' %
# scale)
if scale == 0.:
logging.info('Scale of 0 disables regularizer.')
return lambda _, name=None: None
def mn_i(weights, name=None):
"""Applies max-norm regularization to weights."""
with ops.op_scope([weights], name, 'maxnorm_o_regularizer') as scope:
my_scale = ops.convert_to_tensor(scale,
dtype=weights.dtype.base_dtype,
name='scale')
return standard_ops.mul(my_scale, standard_ops.reduce_sum(standard_ops.reduce_max(standard_ops.abs(weights), 1)), name=scope)
return mn_i
#