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from gcn.inits import *
import tensorflow as tf
flags = tf.app.flags
FLAGS = flags.FLAGS
# global unique layer ID dictionary for layer name assignment
_LAYER_UIDS = {}
def get_layer_uid(layer_name=''):
"""Helper function, assigns unique layer IDs."""
if layer_name not in _LAYER_UIDS:
_LAYER_UIDS[layer_name] = 1
return 1
else:
_LAYER_UIDS[layer_name] += 1
return _LAYER_UIDS[layer_name]
def sparse_dropout(x, keep_prob, noise_shape):
"""Dropout for sparse tensors."""
random_tensor = keep_prob
random_tensor += tf.random_uniform(noise_shape)
dropout_mask = tf.cast(tf.floor(random_tensor), dtype=tf.bool)
pre_out = tf.sparse_retain(x, dropout_mask)
return pre_out * (1./keep_prob)
def dot(x, y, sparse=False):
"""Wrapper for tf.matmul (sparse vs dense)."""
if sparse:
res = tf.sparse_tensor_dense_matmul(x, y)
else:
res = tf.matmul(x, y)
return res
class Layer(object):
"""Base layer class. Defines basic API for all layer objects.
Implementation inspired by keras (http://keras.io).
# Properties
name: String, defines the variable scope of the layer.
logging: Boolean, switches Tensorflow histogram logging on/off
# Methods
_call(inputs): Defines computation graph of layer
(i.e. takes input, returns output)
__call__(inputs): Wrapper for _call()
_log_vars(): Log all variables
"""
def __init__(self, **kwargs):
allowed_kwargs = {'name', 'logging'}
for kwarg in kwargs.keys():
assert kwarg in allowed_kwargs, 'Invalid keyword argument: ' + kwarg
name = kwargs.get('name')
if not name:
layer = self.__class__.__name__.lower()
name = layer + '_' + str(get_layer_uid(layer))
self.name = name
self.vars = {}
logging = kwargs.get('logging', False)
self.logging = logging
self.sparse_inputs = False
def _call(self, inputs):
return inputs
def __call__(self, inputs):
with tf.name_scope(self.name):
if self.logging and not self.sparse_inputs:
tf.summary.histogram(self.name + '/inputs', inputs)
outputs = self._call(inputs)
if self.logging:
tf.summary.histogram(self.name + '/outputs', outputs)
return outputs
def _log_vars(self):
for var in self.vars:
tf.summary.histogram(self.name + '/vars/' + var, self.vars[var])
class Dense(Layer):
"""Dense layer."""
def __init__(self, input_dim, output_dim, placeholders, dropout=0., sparse_inputs=False,
act=tf.nn.relu, bias=False, featureless=False, **kwargs):
super(Dense, self).__init__(**kwargs)
if dropout:
self.dropout = placeholders['dropout']
else:
self.dropout = 0.
self.act = act
self.sparse_inputs = sparse_inputs
self.featureless = featureless
self.bias = bias
# helper variable for sparse dropout
self.num_features_nonzero = placeholders['num_features_nonzero']
with tf.variable_scope(self.name + '_vars'):
self.vars['weights'] = glorot([input_dim, output_dim],
name='weights')
if self.bias:
self.vars['bias'] = zeros([output_dim], name='bias')
if self.logging:
self._log_vars()
def _call(self, inputs):
x = inputs
# dropout
if self.sparse_inputs:
x = sparse_dropout(x, 1-self.dropout, self.num_features_nonzero)
else:
x = tf.nn.dropout(x, 1-self.dropout)
# transform
output = dot(x, self.vars['weights'], sparse=self.sparse_inputs)
# bias
if self.bias:
output += self.vars['bias']
return self.act(output)
class GraphConvolution(Layer):
"""Graph convolution layer."""
def __init__(self, input_dim, output_dim, placeholders, dropout=0.,
sparse_inputs=False, act=tf.nn.relu, bias=False,
featureless=False, **kwargs):
super(GraphConvolution, self).__init__(**kwargs)
if dropout:
self.dropout = placeholders['dropout']
else:
self.dropout = 0.
self.act = act
self.support = placeholders['support']
self.sparse_inputs = sparse_inputs
self.featureless = featureless
self.bias = bias
# helper variable for sparse dropout
self.num_features_nonzero = placeholders['num_features_nonzero']
with tf.variable_scope(self.name + '_vars'):
for i in range(len(self.support)):
self.vars['weights_' + str(i)] = glorot([input_dim, output_dim],
name='weights_' + str(i))
if self.bias:
self.vars['bias'] = zeros([output_dim], name='bias')
if self.logging:
self._log_vars()
def _call(self, inputs):
x = inputs
# dropout
if self.sparse_inputs:
x = sparse_dropout(x, 1-self.dropout, self.num_features_nonzero)
else:
x = tf.nn.dropout(x, 1-self.dropout)
# convolve
supports = list()
for i in range(len(self.support)):
if not self.featureless:
pre_sup = dot(x, self.vars['weights_' + str(i)],
sparse=self.sparse_inputs)
else:
pre_sup = self.vars['weights_' + str(i)]
support = dot(self.support[i], pre_sup, sparse=True)
supports.append(support)
output = tf.add_n(supports)
# bias
if self.bias:
output += self.vars['bias']
return self.act(output)
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