DDPM Tutorials

[ericspod]

Address some of #1769.

Description

These are the 2D and 3D DDPM tutorials. I have run them again to verify they work. The 2D ones are fine but the 3D tutorial keeps having mode collapse or some other issue resulting in bad results. Work is ongoing on this one. I have left the 3D tutorial off since it's not training stably and needs some revamp to be a proper and useful tutorial for users.

Checks

• Avoid including large-size files in the PR.
• Clean up long text outputs from code cells in the notebook.
• For security purposes, please check the contents and remove any sensitive info such as user names and private key.
• Ensure (1) hyperlinks and markdown anchors are working (2) use relative paths for tutorial repo files (3) put figure and graphs in the ./figure folder
• Notebook runs automatically ./runner.sh -t <path to .ipynb file>

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[ericspod]

I'm still trying to get good results for the 3D example so not ready for review yet.

[ericspod]

We're going to leave the 3D tutorial for later, it is not training stably at the moment and isn't a good examplar as a consequence.

[KumoLiu]

Thanks for the PR! Overall looks good to me. Minor comments inline.
And could you please also update the README file here: https://github.com/Project-MONAI/tutorials/blob/main/generation/README.md? Thanks!

[virginiafdez]

Besides existing comments, they look fine by me.

[KumoLiu]

Hi @ericspod, I just disable the auto-merge since the premerge-notebook is not a required one to test. Want to double-confirm. Perhaps we need set it to required test.

[ericspod]

It should be required I'd say, unless there was some reason why notebooks would fail but still be mergable.

[KumoLiu]

It should be required I'd say, unless there was some reason why notebooks would fail but still be mergable.

Let me try whether I have permission to set.