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# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Implementation of Gaussian mixture model (GMM) clustering using tf.Learn."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import numpy as np
from tensorflow.contrib import framework
from tensorflow.contrib.factorization.python.ops import gmm_ops
from tensorflow.contrib.framework.python.framework import checkpoint_utils
from tensorflow.contrib.framework.python.ops import variables
from tensorflow.contrib.learn.python.learn.estimators import estimator
from tensorflow.contrib.learn.python.learn.estimators import model_fn as model_fn_lib
from tensorflow.python.framework import constant_op
from tensorflow.python.ops import array_ops
from tensorflow.python.ops import math_ops
from tensorflow.python.ops import state_ops
from tensorflow.python.ops.control_flow_ops import with_dependencies
def _streaming_sum(scalar_tensor):
"""Create a sum metric and update op."""
sum_metric = framework.local_variable(constant_op.constant(0.0))
sum_update = sum_metric.assign_add(scalar_tensor)
return sum_metric, sum_update
class GMM(estimator.Estimator):
"""An estimator for GMM clustering."""
SCORES = 'scores'
ASSIGNMENTS = 'assignments'
ALL_SCORES = 'all_scores'
def __init__(self,
num_clusters,
model_dir=None,
random_seed=0,
params='wmc',
initial_clusters='random',
covariance_type='full',
config=None):
"""Creates a model for running GMM training and inference.
Args:
num_clusters: number of clusters to train.
model_dir: the directory to save the model results and log files.
random_seed: Python integer. Seed for PRNG used to initialize centers.
params: Controls which parameters are updated in the training process.
Can contain any combination of "w" for weights, "m" for means,
and "c" for covars.
initial_clusters: specifies how to initialize the clusters for training.
See gmm_ops.gmm for the possible values.
covariance_type: one of "full", "diag".
config: See Estimator
"""
self._num_clusters = num_clusters
self._params = params
self._training_initial_clusters = initial_clusters
self._covariance_type = covariance_type
self._training_graph = None
self._random_seed = random_seed
super(GMM, self).__init__(
model_fn=self._model_builder(), model_dir=model_dir, config=config)
def predict_assignments(self, input_fn=None, batch_size=None, outputs=None):
"""See BaseEstimator.predict."""
results = self.predict(input_fn=input_fn,
batch_size=batch_size,
outputs=outputs)
for result in results:
yield result[GMM.ASSIGNMENTS]
def score(self, input_fn=None, batch_size=None, steps=None):
"""Predict total sum of distances to nearest clusters.
Note that this function is different from the corresponding one in sklearn
which returns the negative of the sum of distances.
Args:
input_fn: see predict.
batch_size: see predict.
steps: see predict.
Returns:
Total sum of distances to nearest clusters.
"""
results = self.evaluate(input_fn=input_fn, batch_size=batch_size,
steps=steps)
return np.sum(results[GMM.SCORES])
def clusters(self):
"""Returns cluster centers."""
clusters = checkpoint_utils.load_variable(
self.model_dir, gmm_ops.GmmAlgorithm.CLUSTERS_VARIABLE)
return np.squeeze(clusters, 1)
def covariances(self):
"""Returns the covariances."""
return checkpoint_utils.load_variable(
self.model_dir, gmm_ops.GmmAlgorithm.CLUSTERS_COVS_VARIABLE)
def _parse_tensor_or_dict(self, features):
if isinstance(features, dict):
return array_ops.concat([features[k] for k in sorted(features.keys())],
1)
return features
def _model_builder(self):
"""Creates a model function."""
def _model_fn(features, labels, mode):
"""Model function."""
assert labels is None, labels
(all_scores, model_predictions, losses, training_op) = gmm_ops.gmm(
self._parse_tensor_or_dict(features), self._training_initial_clusters,
self._num_clusters, self._random_seed, self._covariance_type,
self._params)
incr_step = state_ops.assign_add(variables.get_global_step(), 1)
loss = math_ops.reduce_sum(losses)
training_op = with_dependencies([training_op, incr_step], loss)
predictions = {
GMM.ALL_SCORES: all_scores[0],
GMM.ASSIGNMENTS: model_predictions[0][0],
}
eval_metric_ops = {
GMM.SCORES: _streaming_sum(loss),
}
return model_fn_lib.ModelFnOps(mode=mode, predictions=predictions,
eval_metric_ops=eval_metric_ops,
loss=loss, train_op=training_op)
return _model_fn
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