Ogb

This is the second major release of OGB, in which we have curated many more exciting graph datasets, including heterogeneous graphs and a web-scale gigantic graph (100+ million nodes, 1+ billion edges).

First, we note that there is **no change** in the datasets released in version `1.1.1`. Therefore, any experimental results obtained using `1.1.1` on the existing datasets are compatible to version `1.2.0`.

In this new release, we have additionally released **5 new datasets** listed below.
- `ogbn-papers100M`: Web-scale gigantic paper citation network.
- `ogbn-mag`: Heterogeneous academic graph.
- `ogbl-biokg`: Heterogeneous biomedical knowledge graph.
- `ogbl-ddi`: Drug-drug interaction network.
- `ogbg-code`: Source code Abstract Syntax Trees.

OGB package can now automatically fetch the datasets if they have been updated.

First Major Release

This is the first major release of OGB.
A number of changes have been made to the datasets, which are summarized below.

1. Re-indexed all the nodes in the node/link datasets (The graphs remain essentially the same).
2. In dataset folders for all the datasets, added `mapping/` directory that contains information to map node/edge/graph/label indices to real-world entities (e.g., mapping from nodes in PPA to unique protein identifiers, mapping from molecular graphs into the SMILES strings.)
3. Deleted the `ogbn-proteins` node features, and put them in the species variable.
4. Deleted `ogbl-reviews` datasets.
5. Added 4 datasets: `ogbn-arxiv`, `ogbl-citation`, `ogbl-collab`, `ogbl-wikikg`.
6. Renamed `ogbg-ppi` to `ogbg-ppa`.
7. Renamed `ogbg-mol-hiv` and `ogbg-mol-pcba` to `ogbg-molhiv` and `ogbg-molpcba`, respectively.
8. Changed the evaluation metric of imbalanced molecule dataset (e.g., pcba) from ROC-AUC to PRC-AUC.
9. Changed the `get_split_edge()` interface in `LinkPropPredDataset`. The downloaded dataset files are also changed accordingly.
10. Added `num_classes` attribute for multi-class classification datasets.

Minor Changes

OGB datasets can now be imported more conveniently, *e.g.*:
python
from ogb.graphproppred import GraphPropPredDataset
from ogb.graphproppred import PygGraphPropPredDataset
from ogb.graphproppred import DglGraphPropPredDataset

Note that this will throw an `ImportError` if OGB can not find installations of Pyg or DGL, respectively.