Ogb

The dataset downloading now uses http instead of https.

This version provides a major change in `ogbg-code`.

- `ogbg-code` has been deprecated due to prediction target (i.e., method name) leakage in input AST.
- `ogbg-code2` has been introduced that fixes the issue., where the method name and its recursive definition in AST are replaced with a special token `_mask_`.

We sincerely thank Charles Sutton (casutton) for finding the data leakage in our dataset.

This release fixes the dataset bug in negative samples in `ogbl-wikikg` and `ogbl-citation` and releases new versions of them: `ogbl-wikikg2` and `ogbl-citation2`. The old versions are deprecated.

This release enhances the OGB package in the following ways.

- Made `ogbn-papers100M` data loading more tractable by using compressed binary files https://github.com/snap-stanford/ogb/issues/46
- Introduced [DatasetSaver](https://github.com/snap-stanford/ogb/blob/master/ogb/io/README.md) module for external contributors https://github.com/snap-stanford/ogb/issues/1
- Made dataset object compatible to DGL v0.5 (not backward compatible for heterogeneous graph datasets).

This release is mainly for **changing the evaluation metric of `ogbg-molpcba` from PRC-AUC to Average Precision (AP)**. AP is shown to be more appropriate to summarize the non-convex nature of the Precision Recall Curve [1]. The leaderboard and our paper have been updated accordingly.

We also fix an issue and add a feature:
- Fixed an issue for saving a large library-agnostic data object. https://github.com/snap-stanford/ogb/issues/48
- Added automatic version check feature so that users will get notified when the package version is outdated.



[1] Jesse Davis and Mark Goadrich. The relationship between precision-recall and roc curves. InInternational Conference on Machine Learning (ICML), pp. 233–240, 2006.

This release fixes bugs in a dataset, evaluator, and data loader.

- Duplicated edges in `ogbn-mag` are removed. The updated dataset will be downloaded and processed automatically as you run your script for `ogbn-mag`. 40
- Evaluators for `ogbl-collab` and `ogbl-ddi` are updated. Specifically, `ogbl-collab` now uses Hits50, and `ogbl-ddi` now uses Hits20.
- DGL data loader bug for `ogbn-mag` and `ogbl-biokg` is fixed. 36