import re
import torch
from cogdl.data import Data
[docs]class Batch(Data):
r"""A plain old python object modeling a batch of graphs as one big
(dicconnected) graph. With :class:`cogdl.data.Data` being the
base class, all its methods can also be used here.
In addition, single graphs can be reconstructed via the assignment vector
:obj:`batch`, which maps each node to its respective graph identifier.
"""
def __init__(self, batch=None, **kwargs):
super(Batch, self).__init__(**kwargs)
self.batch = batch
self.__data_class__ = Data
self.__slices__ = None
[docs] @staticmethod
def from_data_list(data_list, follow_batch=[]):
r"""Constructs a batch object from a python list holding
:class:`torch_geometric.data.Data` objects.
The assignment vector :obj:`batch` is created on the fly.
Additionally, creates assignment batch vectors for each key in
:obj:`follow_batch`."""
keys = [set(data.keys) for data in data_list]
keys = list(set.union(*keys))
assert "batch" not in keys
batch = Batch()
batch.__data_class__ = data_list[0].__class__
batch.__slices__ = {key: [0] for key in keys}
for key in keys:
batch[key] = []
for key in follow_batch:
batch["{}_batch".format(key)] = []
cumsum = {key: 0 for key in keys}
batch.batch = []
for i, data in enumerate(data_list):
for key in data.keys:
item = data[key]
if torch.is_tensor(item) and item.dtype != torch.bool:
item = item + cumsum[key]
if torch.is_tensor(item):
size = item.size(data.cat_dim(key, data[key]))
else:
size = 1
batch.__slices__[key].append(size + batch.__slices__[key][-1])
cumsum[key] = cumsum[key] + data.__inc__(key, item)
batch[key].append(item)
if key in follow_batch:
item = torch.full((size,), i, dtype=torch.long)
batch["{}_batch".format(key)].append(item)
num_nodes = data.num_nodes
if num_nodes is not None:
item = torch.full((num_nodes,), i, dtype=torch.long)
batch.batch.append(item)
if num_nodes is None:
batch.batch = None
for key in batch.keys:
item = batch[key][0]
if torch.is_tensor(item):
batch[key] = torch.cat(batch[key], dim=data_list[0].cat_dim(key, item))
elif isinstance(item, int) or isinstance(item, float):
batch[key] = torch.tensor(batch[key])
return batch.contiguous()
[docs] def cumsum(self, key, item):
r"""If :obj:`True`, the attribute :obj:`key` with content :obj:`item`
should be added up cumulatively before concatenated together.
.. note::
This method is for internal use only, and should only be overridden
if the batch concatenation process is corrupted for a specific data
attribute.
"""
return bool(re.search("(index|face)", key))
@property
def num_graphs(self):
"""Returns the number of graphs in the batch."""
return self.batch[-1].item() + 1