add SGC-PN model

[yaofeng1998]

Based on PairNorm: Tackling Oversmoothing in GNNs (link: https://arxiv.org/abs/1909.12223, source code: https://github.com/LingxiaoShawn/PairNorm)
Contributor: Yao Feng

[cenyk1230]

Hi @feng-y16,

Thank you for contributing to the CogDL. The model should be also tested. You can add one test in tests/tasks/node_classification.py to ensure the model is covered in the testing. In the meanwhile, you should add the results of the new model to our leaderboard in the README (https://github.com/THUDM/cogdl#semi-supervised-node-classification-with-attributes).

[cenyk1230]

Are there any ways to add only three datasets (cora-missing, citeseer-missing, and pubmed-missing) and pass the missing rate (0/20/40/60/80/100) as input arguments?

[yaofeng1998]

I see. It seems that the dataset classes cannot add arguments to the parser, so I am not sure.

[cenyk1230]

Sorry, I will try to implement the feature to support dataset arguments.

[cenyk1230]

Maybe we can add the missing rate argument in the node_classification task and process the data in the __init__ function of node_classification task.

[yaofeng1998]

I fixed the issues.

[cenyk1230]

From the build, it seems you should set missing_rate=-1 in the get_default_args in the test_node_classification.py.