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training.py
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training.py
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# -*- coding: utf-8 -*-
"""Training-related part of the Keras engine.
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import warnings
import copy
import numpy as np
from scipy.sparse import issparse
from .topology import Container
from .. import backend as K
from .. import optimizers
from .. import losses
from .. import metrics as metrics_module
from ..utils.data_utils import Sequence
from ..utils.data_utils import GeneratorEnqueuer
from ..utils.data_utils import OrderedEnqueuer
from ..utils.generic_utils import Progbar
from .. import callbacks as cbks
from ..legacy import interfaces
def _standardize_input_data(data, names, shapes=None,
check_batch_axis=True,
exception_prefix=''):
"""Normalizes inputs and targets provided by users.
Users may pass data as a list of arrays, dictionary of arrays,
or as a single array. We normalize this to an ordered list of
arrays (same order as `names`), while checking that the provided
arrays have shapes that match the network's expectations.
# Arguments
data: User-provided input data (polymorphic).
names: List of expected array names.
shapes: Optional list of expected array shapes.
check_batch_axis: Boolean; whether to check that
the batch axis of the arrays matches the expected
value found in `shapes`.
exception_prefix: String prefix used for exception formatting.
# Returns
List of standardized input arrays (one array per model input).
# Raises
ValueError: in case of improperly formatted user-provided data.
"""
if not names:
if data is not None and hasattr(data, '__len__') and len(data):
raise ValueError('Error when checking model ' +
exception_prefix + ': '
'expected no data, but got:', data)
return []
if data is None:
return [None for _ in range(len(names))]
if isinstance(data, dict):
try:
data = [data[x].values if data[x].__class__.__name__ == 'DataFrame' else data[x] for x in names]
except KeyError as e:
raise ValueError(
'No data provided for "' + e.args[0] + '". Need data '
'for each key in: ' + str(names))
elif isinstance(data, list):
if len(names) == 1 and data and isinstance(data[0], (float, int)):
data = [np.asarray(data)]
else:
data = [x.values if x.__class__.__name__ == 'DataFrame' else x for x in data]
else:
data = data.values if data.__class__.__name__ == 'DataFrame' else data
data = [data]
data = [np.expand_dims(x, 1) if x is not None and x.ndim == 1 else x for x in data]
if len(data) != len(names):
if data and hasattr(data[0], 'shape'):
raise ValueError(
'Error when checking model ' + exception_prefix +
': the list of Numpy arrays that you are passing to '
'your model is not the size the model expected. '
'Expected to see ' + str(len(names)) + ' array(s), '
'but instead got the following list of ' +
str(len(data)) + ' arrays: ' + str(data)[:200] + '...')
elif len(names) > 1:
raise ValueError(
'Error when checking model ' + exception_prefix +
': you are passing a list as input to your model, '
'but the model expects a list of ' + str(len(names)) +
' Numpy arrays instead. The list you passed was: ' +
str(data)[:200])
elif len(data) == 1 and not hasattr(data[0], 'shape'):
raise TypeError(
'Error when checking model ' + exception_prefix +
': data should be a Numpy array, or list/dict of '
'Numpy arrays. Found: ' + str(data)[:200] + '...')
elif len(names) == 1:
data = [np.asarray(data)]
# Check shapes compatibility.
if shapes:
for i in range(len(names)):
if shapes[i] is not None:
data_shape = data[i].shape
shape = shapes[i]
if data[i].ndim != len(shape):
raise ValueError(
'Error when checking ' + exception_prefix +
': expected ' + names[i] + ' to have ' +
str(len(shape)) + ' dimensions, but got array '
'with shape ' + str(data_shape))
if not check_batch_axis:
data_shape = data_shape[1:]
shape = shape[1:]
for dim, ref_dim in zip(data_shape, shape):
if ref_dim != dim and ref_dim:
raise ValueError(
'Error when checking ' + exception_prefix +
': expected ' + names[i] + ' to have shape ' +
str(shape) + ' but got array with shape ' +
str(data_shape))
return data
def _standardize_sample_or_class_weights(x_weight, output_names, weight_type):
"""Maps `sample_weight` or `class_weight` to model outputs.
# Arguments
x_weight: User-provided `sample_weight` or `class_weight` argument.
output_names: List of output names (strings) in the model.
weight_type: A string used purely for exception printing.
# Returns
A list of `sample_weight` or `class_weight` where there are exactly
one element per model output.
# Raises
ValueError: In case of invalid user-provided argument.
"""
if x_weight is None or len(x_weight) == 0:
return [None for _ in output_names]
if len(output_names) == 1:
if isinstance(x_weight, list) and len(x_weight) == 1:
return x_weight
if isinstance(x_weight, dict) and output_names[0] in x_weight:
return [x_weight[output_names[0]]]
else:
return [x_weight]
if isinstance(x_weight, list):
if len(x_weight) != len(output_names):
raise ValueError('Provided `' + weight_type + '` was a list of ' +
str(len(x_weight)) +
' elements, but the model has ' +
str(len(output_names)) + ' outputs. '
'You should provide one `' + weight_type + '`'
'array per model output.')
return x_weight
if isinstance(x_weight, dict):
x_weights = []
for name in output_names:
x_weights.append(x_weight.get(name))
return x_weights
else:
raise TypeError('The model has multiple outputs, so `' +
weight_type + '` '
'should be either a list or a dict. '
'Provided `' + weight_type +
'` type not understood: ' +
str(x_weight))
def _standardize_class_weights(class_weight, output_names):
return _standardize_sample_or_class_weights(class_weight,
output_names,
'class_weight')
def _standardize_sample_weights(sample_weight, output_names):
return _standardize_sample_or_class_weights(sample_weight,
output_names,
'sample_weight')
def _check_array_lengths(inputs, targets, weights=None):
"""Checks if batch axes are the same for numpy arrays.
# Arguments
inputs: list of Numpy arrays of inputs.
targets: list of Numpy arrays of targets.
weights: list of Numpy arrays of sample weights.
# Raises
ValueError: in case of incorrectly formatted data.
"""
def set_of_lengths(x):
# return a set with the variation between
# different shapes, with None => 0
if x is None:
return {0}
else:
return set([0 if y is None else y.shape[0] for y in x])
set_x = set_of_lengths(inputs)
set_y = set_of_lengths(targets)
set_w = set_of_lengths(weights)
if len(set_x) > 1:
raise ValueError('All input arrays (x) should have '
'the same number of samples. Got array shapes: ' +
str([x.shape for x in inputs]))
if len(set_y) > 1:
raise ValueError('All target arrays (y) should have '
'the same number of samples. Got array shapes: ' +
str([y.shape for y in targets]))
if set_x and set_y and list(set_x)[0] != list(set_y)[0]:
raise ValueError('Input arrays should have '
'the same number of samples as target arrays. '
'Found ' + str(list(set_x)[0]) + ' input samples '
'and ' + str(list(set_y)[0]) + ' target samples.')
if len(set_w) > 1:
raise ValueError('All sample_weight arrays should have '
'the same number of samples. Got array shapes: ' +
str([w.shape for w in weights]))
if set_y and set_w and list(set_y)[0] != list(set_w)[0]:
raise ValueError('Sample_weight arrays should have '
'the same number of samples as target arrays. Got ' +
str(list(set_y)[0]) + ' input samples and ' +
str(list(set_w)[0]) + ' target samples.')
def _check_loss_and_target_compatibility(targets, loss_fns, output_shapes):
"""Does validation on the compatibility of targets and loss functions.
This helps prevent users from using loss functions incorrectly.
# Arguments
targets: list of Numpy arrays of targets.
loss_fns: list of loss functions.
output_shapes: list of shapes of model outputs.
# Raises
ValueError: if a loss function or target array
is incompatible with an output.
"""
key_losses = {losses.mean_squared_error,
losses.binary_crossentropy,
losses.categorical_crossentropy}
for y, loss, shape in zip(targets, loss_fns, output_shapes):
if y is None or loss is None:
continue
if loss is losses.categorical_crossentropy:
if y.shape[-1] == 1:
raise ValueError(
'You are passing a target array of shape ' + str(y.shape) +
' while using as loss `categorical_crossentropy`. '
'`categorical_crossentropy` expects '
'targets to be binary matrices (1s and 0s) '
'of shape (samples, classes). '
'If your targets are integer classes, '
'you can convert them to the expected format via:\n'
'```\n'
'from keras.utils import to_categorical\n'
'y_binary = to_categorical(y_int)\n'
'```\n'
'\n'
'Alternatively, you can use the loss function '
'`sparse_categorical_crossentropy` instead, '
'which does expect integer targets.')
if loss in key_losses:
for target_dim, out_dim in zip(y.shape[1:], shape[1:]):
if out_dim is not None and target_dim != out_dim:
raise ValueError(
'A target array with shape ' + str(y.shape) +
' was passed for an output of shape ' + str(shape) +
' while using as loss `' + loss.__name__ + '`. '
'This loss expects '
'targets to have the same shape '
'as the output.')
def _collect_metrics(metrics, output_names):
"""Maps metric functions to model outputs.
# Arguments
metrics: a list or dict of metric functions.
output_names: a list of the names (strings) of model outputs.
# Returns
A list (one entry per model output) of lists of metric functions.
For instance, if the model has 2 outputs, and for the first output
we want to compute "binary_accuracy" and "binary_crossentropy",
and just "binary_accuracy" for the second output,
the list would look like:
`[[binary_accuracy, binary_crossentropy], [binary_accuracy]]`
# Raises
TypeError: if an incorrect type is passed for the `metrics` argument.
"""
if not metrics:
return [[] for _ in output_names]
if isinstance(metrics, list):
# we then apply all metrics to all outputs.
return [copy.copy(metrics) for _ in output_names]
elif isinstance(metrics, dict):
nested_metrics = []
for name in output_names:
output_metrics = metrics.get(name, [])
if not isinstance(output_metrics, list):
output_metrics = [output_metrics]
nested_metrics.append(output_metrics)
return nested_metrics
else:
raise TypeError('Type of `metrics` argument not understood. '
'Expected a list or dictionary, found: ' +
str(metrics))
def _batch_shuffle(index_array, batch_size):
"""Shuffles an array in a batch-wise fashion.
Useful for shuffling HDF5 arrays
(where one cannot access arbitrary indices).
# Arguments
index_array: array of indices to be shuffled.
batch_size: integer.
# Returns
The `index_array` array, shuffled in a batch-wise fashion.
"""
batch_count = int(len(index_array) / batch_size)
# to reshape we need to be cleanly divisible by batch size
# we stash extra items and reappend them after shuffling
last_batch = index_array[batch_count * batch_size:]
index_array = index_array[:batch_count * batch_size]
index_array = index_array.reshape((batch_count, batch_size))
np.random.shuffle(index_array)
index_array = index_array.flatten()
return np.append(index_array, last_batch)
def _make_batches(size, batch_size):
"""Returns a list of batch indices (tuples of indices).
# Arguments
size: Integer, total size of the data to slice into batches.
batch_size: Integer, batch size.
# Returns
A list of tuples of array indices.
"""
num_batches = (size + batch_size - 1) // batch_size # round up
return [(i * batch_size, min(size, (i + 1) * batch_size))
for i in range(num_batches)]
def _slice_arrays(arrays, start=None, stop=None):
"""Slice an array or list of arrays.
This takes an array-like, or a list of
array-likes, and outputs:
- arrays[start:stop] if `arrays` is an array-like
- [x[start:stop] for x in arrays] if `arrays` is a list
Can also work on list/array of indices: `_slice_arrays(x, indices)`
# Arguments
arrays: Single array or list of arrays.
start: can be an integer index (start index)
or a list/array of indices
stop: integer (stop index); should be None if
`start` was a list.
# Returns
A slice of the array(s).
"""
if arrays is None:
return [None]
elif isinstance(arrays, list):
if hasattr(start, '__len__'):
# hdf5 datasets only support list objects as indices
if hasattr(start, 'shape'):
start = start.tolist()
return [None if x is None else x[start] for x in arrays]
else:
return [None if x is None else x[start:stop] for x in arrays]
else:
if hasattr(start, '__len__'):
if hasattr(start, 'shape'):
start = start.tolist()
return arrays[start]
elif hasattr(start, '__getitem__'):
return arrays[start:stop]
else:
return [None]
def _weighted_masked_objective(fn):
"""Adds support for masking and sample-weighting to an objective function.
It transforms an objective function `fn(y_true, y_pred)`
into a sample-weighted, cost-masked objective function
`fn(y_true, y_pred, weights, mask)`.
# Arguments
fn: The objective function to wrap,
with signature `fn(y_true, y_pred)`.
# Returns
A function with signature `fn(y_true, y_pred, weights, mask)`.
"""
if fn is None:
return None
def weighted(y_true, y_pred, weights, mask=None):
"""Wrapper function.
# Arguments
y_true: `y_true` argument of `fn`.
y_pred: `y_pred` argument of `fn`.
weights: Weights tensor.
mask: Mask tensor.
# Returns
Scalar tensor.
"""
# score_array has ndim >= 2
score_array = fn(y_true, y_pred)
if mask is not None:
# Cast the mask to floatX to avoid float64 upcasting in Theano
mask = K.cast(mask, K.floatx())
# mask should have the same shape as score_array
score_array *= mask
# the loss per batch should be proportional
# to the number of unmasked samples.
score_array /= K.mean(mask)
# apply sample weighting
if weights is not None:
# reduce score_array to same ndim as weight array
ndim = K.ndim(score_array)
weight_ndim = K.ndim(weights)
score_array = K.mean(score_array, axis=list(range(weight_ndim, ndim)))
score_array *= weights
score_array /= K.mean(K.cast(K.not_equal(weights, 0), K.floatx()))
return K.mean(score_array)
return weighted
def _standardize_weights(y, sample_weight=None, class_weight=None,
sample_weight_mode=None):
"""Performs sample weight validation and standardization.
Everything gets normalized to a single sample-wise (or timestep-wise)
weight array.
# Arguments
y: Numpy array of model targets to be weighted.
sample_weight: User-provided `sample_weight` argument.
class_weight: User-provided `class_weight` argument.
sample_weight_mode: One of `None` or `"temporal"`.
`"temporal"` indicated that we expect 2D weight data
that will be applied to the last 2 dimensions of
the targets (i.e. we are weighting timesteps, not samples).
# Returns
A numpy array of target weights, one entry per sample to weight.
# Raises
ValueError: In case of invalid user-provided arguments.
"""
if sample_weight_mode is not None:
if sample_weight_mode != 'temporal':
raise ValueError('"sample_weight_mode '
'should be None or "temporal". '
'Found: ' + str(sample_weight_mode))
if len(y.shape) < 3:
raise ValueError('Found a sample_weight array for '
'an input with shape ' +
str(y.shape) + '. '
'Timestep-wise sample weighting (use of '
'sample_weight_mode="temporal") is restricted to '
'outputs that are at least 3D, i.e. that have '
'a time dimension.')
if sample_weight is not None and len(sample_weight.shape) != 2:
raise ValueError('Found a sample_weight array with shape ' +
str(sample_weight.shape) + '. '
'In order to use timestep-wise sample weighting, '
'you should pass a 2D sample_weight array.')
else:
if sample_weight is not None and len(sample_weight.shape) != 1:
raise ValueError('Found a sample_weight array with shape ' +
str(sample_weight.shape) + '. '
'In order to use timestep-wise sample weights, '
'you should specify '
'sample_weight_mode="temporal" '
'in compile(). If you just mean to use '
'sample-wise weights, make sure your '
'sample_weight array is 1D.')
if sample_weight is not None:
if len(sample_weight.shape) > len(y.shape):
raise ValueError('Found a sample_weight with shape' +
str(sample_weight.shape) + '.'
'Expected sample_weight with rank '
'less than or equal to ' + str(len(y.shape)))
if y.shape[:sample_weight.ndim] != sample_weight.shape:
raise ValueError('Found a sample_weight array with shape ' +
str(sample_weight.shape) + ' for an input with shape ' +
str(y.shape) + '. '
'sample_weight cannot be broadcast.')
return sample_weight
elif isinstance(class_weight, dict):
if len(y.shape) > 2:
raise ValueError('`class_weight` not supported for '
'3+ dimensional targets.')
if y.shape[1] > 1:
y_classes = np.argmax(y, axis=1)
elif y.shape[1] == 1:
y_classes = np.reshape(y, y.shape[0])
else:
y_classes = y
weights = np.asarray([class_weight[cls] for cls in y_classes
if cls in class_weight])
if len(weights) != len(y_classes):
# subtract the sets to pick all missing classes
existing_classes = set(y_classes)
existing_class_weight = set(class_weight.keys())
raise ValueError('`class_weight` must contain all classes in the data.'
' The classes %s exist in the data but not in '
'`class_weight`.'
% (existing_classes - existing_class_weight))
return weights
else:
if sample_weight_mode is None:
return np.ones((y.shape[0],), dtype=K.floatx())
else:
return np.ones((y.shape[0], y.shape[1]), dtype=K.floatx())
class Model(Container):
"""The `Model` class adds training & evaluation routines to a `Container`.
"""
def compile(self, optimizer, loss=None, metrics=None, loss_weights=None,
sample_weight_mode=None, weighted_metrics=None,
target_tensors=None, **kwargs):
"""Configures the model for training.
# Arguments
optimizer: String (name of optimizer) or optimizer instance.
See [optimizers](/optimizers).
loss: String (name of objective function) or objective function.
See [losses](/losses).
If the model has multiple outputs, you can use a different loss
on each output by passing a dictionary or a list of losses.
The loss value that will be minimized by the model
will then be the sum of all individual losses.
metrics: List of metrics to be evaluated by the model
during training and testing.
Typically you will use `metrics=['accuracy']`.
To specify different metrics for different outputs of a
multi-output model, you could also pass a dictionary,
such as `metrics={'output_a': 'accuracy'}`.
loss_weights: Optional list or dictionary specifying scalar
coefficients (Python floats) to weight the loss contributions
of different model outputs.
The loss value that will be minimized by the model
will then be the *weighted sum* of all individual losses,
weighted by the `loss_weights` coefficients.
If a list, it is expected to have a 1:1 mapping
to the model's outputs. If a tensor, it is expected to map
output names (strings) to scalar coefficients.
sample_weight_mode: If you need to do timestep-wise
sample weighting (2D weights), set this to `"temporal"`.
`None` defaults to sample-wise weights (1D).
If the model has multiple outputs, you can use a different
`sample_weight_mode` on each output by passing a
dictionary or a list of modes.
weighted_metrics: List of metrics to be evaluated and weighted
by sample_weight or class_weight during training and testing.
target_tensors: By default, Keras will create placeholders for the
model's target, which will be fed with the target data during
training. If instead you would like to use your own
target tensors (in turn, Keras will not expect external
Numpy data for these targets at training time), you
can specify them via the `target_tensors` argument. It can be
a single tensor (for a single-output model), a list of tensors,
or a dict mapping output names to target tensors.
**kwargs: When using the Theano/CNTK backends, these arguments
are passed into `K.function`.
When using the TensorFlow backend,
these arguments are passed into `tf.Session.run`.
# Raises
ValueError: In case of invalid arguments for
`optimizer`, `loss`, `metrics` or `sample_weight_mode`.
"""
loss = loss or {}
self.optimizer = optimizers.get(optimizer)
self.loss = loss
self.loss_weights = loss_weights
self.sample_weight_mode = sample_weight_mode
# Prepare loss functions.
if isinstance(loss, dict):
for name in loss:
if name not in self.output_names:
raise ValueError('Unknown entry in loss '
'dictionary: "' + name + '". '
'Only expected the following keys: ' +
str(self.output_names))
loss_functions = []
for name in self.output_names:
if name not in loss:
warnings.warn('Output "' + name +
'" missing from loss dictionary. '
'We assume this was done on purpose, '
'and we will not be expecting '
'any data to be passed to "' + name +
'" during training.', stacklevel=2)
loss_functions.append(losses.get(loss.get(name)))
elif isinstance(loss, list):
if len(loss) != len(self.outputs):
raise ValueError('When passing a list as loss, '
'it should have one entry per model outputs. '
'The model has ' + str(len(self.outputs)) +
' outputs, but you passed loss=' +
str(loss))
loss_functions = [losses.get(l) for l in loss]
else:
loss_function = losses.get(loss)
loss_functions = [loss_function for _ in range(len(self.outputs))]
self.loss_functions = loss_functions
weighted_losses = [_weighted_masked_objective(fn) for fn in loss_functions]
skip_target_indices = []
skip_target_weighing_indices = []
self._feed_outputs = []
self._feed_output_names = []
self._feed_output_shapes = []
self._feed_loss_fns = []
for i in range(len(weighted_losses)):
if weighted_losses[i] is None:
skip_target_indices.append(i)
skip_target_weighing_indices.append(i)
# Prepare output masks.
masks = self.compute_mask(self.inputs, mask=None)
if masks is None:
masks = [None for _ in self.outputs]
if not isinstance(masks, list):
masks = [masks]
# Prepare loss weights.
if loss_weights is None:
loss_weights_list = [1. for _ in range(len(self.outputs))]
elif isinstance(loss_weights, dict):
for name in loss_weights:
if name not in self.output_names:
raise ValueError('Unknown entry in loss_weights '
'dictionary: "' + name + '". '
'Only expected the following keys: ' +
str(self.output_names))
loss_weights_list = []
for name in self.output_names:
loss_weights_list.append(loss_weights.get(name, 1.))
elif isinstance(loss_weights, list):
if len(loss_weights) != len(self.outputs):
raise ValueError('When passing a list as loss_weights, '
'it should have one entry per model output. '
'The model has ' + str(len(self.outputs)) +
' outputs, but you passed loss_weights=' +
str(loss_weights))
loss_weights_list = loss_weights
else:
raise TypeError('Could not interpret loss_weights argument: ' +
str(loss_weights) +
' - expected a list of dicts.')
# Prepare targets of model.
self.targets = []
self._feed_targets = []
if target_tensors is not None:
if isinstance(target_tensors, list):
if len(target_tensors) != len(self.outputs):
raise ValueError(
'When passing a list as `target_tensors`, '
'it should have one entry per model output. '
'The model has ' + str(len(self.outputs)) +
' outputs, but you passed target_tensors=' +
str(target_tensors))
elif isinstance(target_tensors, dict):
for name in target_tensors:
if name not in self.output_names:
raise ValueError('Unknown entry in `target_tensors` '
'dictionary: "' + name + '". '
'Only expected the following keys: ' +
str(self.output_names))
tmp_target_tensors = []
for name in self.output_names:
tmp_target_tensors.append(target_tensors.get(name, None))
target_tensors = tmp_target_tensors
else:
raise TypeError('Expected `target_tensors` to be '
'a list or dict, but got:', target_tensors)
for i in range(len(self.outputs)):
if i in skip_target_indices:
self.targets.append(None)
else:
shape = self._internal_output_shapes[i]
name = self.output_names[i]
if target_tensors is not None:
target = target_tensors[i]
else:
target = None
if target is None or K.is_placeholder(target):
if target is None:
target = K.placeholder(ndim=len(shape),
name=name + '_target',
sparse=K.is_sparse(self.outputs[i]),
dtype=K.dtype(self.outputs[i]))
self._feed_targets.append(target)
self._feed_outputs.append(self.outputs[i])
self._feed_output_names.append(name)
self._feed_output_shapes.append(shape)
self._feed_loss_fns.append(self.loss_functions[i])
else:
skip_target_weighing_indices.append(i)
self.targets.append(target)
# Prepare sample weights.
sample_weights = []
sample_weight_modes = []
if isinstance(sample_weight_mode, dict):
for name in sample_weight_mode:
if name not in self.output_names:
raise ValueError('Unknown entry in '
'sample_weight_mode dictionary: "' +
name + '". '
'Only expected the following keys: ' +
str(self.output_names))
for i, name in enumerate(self.output_names):
if i in skip_target_weighing_indices:
weight = None
sample_weight_modes.append(None)
else:
if name not in sample_weight_mode:
raise ValueError('Output "' + name +
'" missing from sample_weight_modes '
'dictionary')
if sample_weight_mode.get(name) == 'temporal':
weight = K.placeholder(ndim=2,
name=name + '_sample_weights')
sample_weight_modes.append('temporal')
else:
weight = K.placeholder(ndim=1,
name=name + '_sample_weights')
sample_weight_modes.append(None)
sample_weights.append(weight)
elif isinstance(sample_weight_mode, list):
if len(sample_weight_mode) != len(self.outputs):
raise ValueError('When passing a list as sample_weight_mode, '
'it should have one entry per model output. '
'The model has ' + str(len(self.outputs)) +
' outputs, but you passed '
'sample_weight_mode=' +
str(sample_weight_mode))
for i in range(len(self.output_names)):
if i in skip_target_weighing_indices:
weight = None
sample_weight_modes.append(None)
else:
mode = sample_weight_mode[i]
name = self.output_names[i]
if mode == 'temporal':
weight = K.placeholder(ndim=2,
name=name + '_sample_weights')
sample_weight_modes.append('temporal')
else:
weight = K.placeholder(ndim=1,
name=name + '_sample_weights')
sample_weight_modes.append(None)
sample_weights.append(weight)
else:
for i, name in enumerate(self.output_names):
if i in skip_target_weighing_indices:
sample_weight_modes.append(None)
sample_weights.append(None)
else:
if sample_weight_mode == 'temporal':
sample_weights.append(
K.placeholder(ndim=2,
name=name + '_sample_weights'))
sample_weight_modes.append('temporal')
else:
sample_weights.append(
K.placeholder(ndim=1,
name=name + '_sample_weights'))
sample_weight_modes.append(None)
self.sample_weight_modes = sample_weight_modes
self._feed_sample_weight_modes = []
for i in range(len(self.outputs)):
if i not in skip_target_weighing_indices:
self._feed_sample_weight_modes.append(self.sample_weight_modes[i])
# Prepare metrics.
self.metrics = metrics
self.weighted_metrics = weighted_metrics
self.metrics_names = ['loss']
self.metrics_tensors = []
# Compute total loss.
total_loss = None
with K.name_scope('loss'):
for i in range(len(self.outputs)):
if i in skip_target_indices:
continue
y_true = self.targets[i]
y_pred = self.outputs[i]
weighted_loss = weighted_losses[i]
sample_weight = sample_weights[i]
mask = masks[i]
loss_weight = loss_weights_list[i]
with K.name_scope(self.output_names[i] + '_loss'):
output_loss = weighted_loss(y_true, y_pred,
sample_weight, mask)
if len(self.outputs) > 1:
self.metrics_tensors.append(output_loss)
self.metrics_names.append(self.output_names[i] + '_loss')
if total_loss is None:
total_loss = loss_weight * output_loss
else:
total_loss += loss_weight * output_loss
if total_loss is None:
if not self.losses:
raise ValueError('The model cannot be compiled '
'because it has no loss to optimize.')
else:
total_loss = 0.
# Add regularization penalties
# and other layer-specific losses.
for loss_tensor in self.losses:
total_loss += loss_tensor
# List of same size as output_names.
# contains tuples (metrics for output, names of metrics).
nested_metrics = _collect_metrics(metrics, self.output_names)
nested_weighted_metrics = _collect_metrics(weighted_metrics, self.output_names)
def append_metric(layer_index, metric_name, metric_tensor):
"""Helper function used in loop below."""
if len(self.output_names) > 1:
metric_name = self.output_names[layer_index] + '_' + metric_name
self.metrics_names.append(metric_name)
self.metrics_tensors.append(metric_tensor)
with K.name_scope('metrics'):
for i in range(len(self.outputs)):
if i in skip_target_indices:
continue
y_true = self.targets[i]
y_pred = self.outputs[i]
weights = sample_weights[i]
output_metrics = nested_metrics[i]
output_weighted_metrics = nested_weighted_metrics[i]
def handle_metrics(metrics, weights=None):
metric_name_prefix = 'weighted_' if weights is not None else ''
for metric in metrics:
if metric in ('accuracy', 'acc', 'crossentropy', 'ce'):
# custom handling of accuracy/crossentropy
# (because of class mode duality)
output_shape = self._internal_output_shapes[i]
if (output_shape[-1] == 1 or
self.loss_functions[i] == losses.binary_crossentropy):
# case: binary accuracy/crossentropy
if metric in ('accuracy', 'acc'):
acc_fn = metrics_module.binary_accuracy
elif metric in ('crossentropy', 'ce'):
acc_fn = metrics_module.binary_crossentropy
elif self.loss_functions[i] == losses.sparse_categorical_crossentropy:
# case: categorical accuracy/crossentropy with sparse targets
if metric in ('accuracy', 'acc'):
acc_fn = metrics_module.sparse_categorical_accuracy
elif metric in ('crossentropy', 'ce'):
acc_fn = metrics_module.sparse_categorical_crossentropy
else:
# case: categorical accuracy/crossentropy
if metric in ('accuracy', 'acc'):
acc_fn = metrics_module.categorical_accuracy
elif metric in ('crossentropy', 'ce'):
acc_fn = metrics_module.categorical_crossentropy
if metric in ('accuracy', 'acc'):
suffix = 'acc'
elif metric in ('crossentropy', 'ce'):
suffix = 'ce'
weighted_metric_fn = _weighted_masked_objective(acc_fn)
metric_name = metric_name_prefix + suffix
else:
metric_fn = metrics_module.get(metric)
weighted_metric_fn = _weighted_masked_objective(metric_fn)
metric_name = metric_name_prefix + metric_fn.__name__
with K.name_scope(metric_name):
metric_result = weighted_metric_fn(y_true, y_pred,
weights=weights,
mask=masks[i])
append_metric(i, metric_name, metric_result)
handle_metrics(output_metrics)
handle_metrics(output_weighted_metrics, weights=weights)
# Prepare gradient updates and state updates.
self.total_loss = total_loss
self.sample_weights = sample_weights
self._feed_sample_weights = []
for i in range(len(self.sample_weights)):
if i not in skip_target_weighing_indices:
self._feed_sample_weights.append(sample_weights[i])
# Functions for train, test and predict will
# be compiled lazily when required.
# This saves time when the user is not using all functions.
self._function_kwargs = kwargs
self.train_function = None
self.test_function = None
self.predict_function = None
# Collected trainable weights, sorted in topological order.
trainable_weights = self.trainable_weights
self._collected_trainable_weights = trainable_weights
def _check_trainable_weights_consistency(self):
"""Check trainable weights count consistency.
This will raise a warning if `trainable_weights` and
`_collected_trainable_weights` are inconsistent (i.e. have different
number of parameters).
Inconsistency will typically arise when one modifies `model.trainable`
without calling `model.compile` again.
"""
if not hasattr(self, '_collected_trainable_weights'):
return
if (len(self.trainable_weights) !=
len(self._collected_trainable_weights)):
warnings.warn(UserWarning(
'Discrepancy between trainable weights and collected trainable'
' weights, did you set `model.trainable` without calling'
' `model.compile` after ?'))
def _make_train_function(self):
if not hasattr(self, 'train_function'):
raise RuntimeError('You must compile your model before using it.')
self._check_trainable_weights_consistency()
if self.train_function is None:
inputs = self._feed_inputs + self._feed_targets + self._feed_sample_weights
if self.uses_learning_phase and not isinstance(K.learning_phase(), int):
inputs += [K.learning_phase()]
with K.name_scope('training'):
with K.name_scope(self.optimizer.__class__.__name__):
training_updates = self.optimizer.get_updates(
params=self._collected_trainable_weights,
loss=self.total_loss)
updates = self.updates + training_updates
# Gets loss and metrics. Updates weights at each call.
self.train_function = K.function(inputs,
[self.total_loss] + self.metrics_tensors,
updates=updates,
name='train_function',
**self._function_kwargs)
def _make_test_function(self):
if not hasattr(self, 'test_function'):
raise RuntimeError('You must compile your model before using it.')
if self.test_function is None:
inputs = self._feed_inputs + self._feed_targets + self._feed_sample_weights
if self.uses_learning_phase and not isinstance(K.learning_phase(), int):
inputs += [K.learning_phase()]
# Return loss and metrics, no gradient updates.
# Does update the network states.
self.test_function = K.function(inputs,
[self.total_loss] + self.metrics_tensors,
updates=self.state_updates,
name='test_function',
**self._function_kwargs)
def _make_predict_function(self):
if not hasattr(self, 'predict_function'):
self.predict_function = None
if self.predict_function is None:
if self.uses_learning_phase and not isinstance(K.learning_phase(), int):