def signature(self):
"""
This property computes the signature of the dataset, which can be
passed to `spektral.data.utils.to_tf_signature(signature)` to compute
the TensorFlow signature. You can safely ignore this property unless
you are creating a custom `Loader`.
A signature consist of the TensorFlow TypeSpec, shape, and dtype of
all characteristic matrices of the graphs in the Dataset. This is
returned as a dictionary of dictionaries, with keys `x`, `a`, `e`, and
`y` for the four main data matrices.
Each sub-dictionary will have keys `spec`, `shape` and `dtype`.
"""
if len(self.graphs) == 0:
return None
signature = {}
graph = self.graphs[0] # This is always non-empty
if graph.x is not None:
signature["x"] = dict()
signature["x"]["spec"] = get_spec(graph.x)
signature["x"]["shape"] = (None, self.n_node_features)
signature["x"]["dtype"] = tf.as_dtype(graph.x.dtype)
if graph.a is not None:
signature["a"] = dict()
signature["a"]["spec"] = get_spec(graph.a)
signature["a"]["shape"] = (None, None)
signature["a"]["dtype"] = tf.as_dtype(graph.a.dtype)
if graph.e is not None:
signature["e"] = dict()
signature["e"]["spec"] = get_spec(graph.e)
signature["e"]["shape"] = (None, self.n_edge_features)
signature["e"]["dtype"] = tf.as_dtype(graph.e.dtype)
if graph.y is not None:
signature["y"] = dict()
signature["y"]["spec"] = get_spec(graph.y)
signature["y"]["shape"] = (self.n_labels, )
signature["y"]["dtype"] = tf.as_dtype(np.array(graph.y).dtype)
return signature
def tf_signature(self):
"""
Adjacency matrix has shape [n_nodes, n_nodes]
Node features have shape [batch, n_nodes, n_node_features]
Edge features have shape [batch, n_edges, n_edge_features]
Targets have shape [batch, ..., n_labels]
"""
signature = self.dataset.signature
for k in ["x", "e", "y"]:
if k in signature:
signature[k]["shape"] = prepend_none(signature[k]["shape"])
signature["a"] = dict()
signature["a"]["spec"] = get_spec(self.dataset.a)
signature["a"]["shape"] = (None, None)
signature["a"]["dtype"] = tf.as_dtype(self.dataset.a.dtype)
return to_tf_signature(signature)