[Core] Possible issue with core.py

[mnajaria]

What happened + What you expected to happen

It seems that in the following link we should replace the Y_df with Y_hat_df. In core.py it should change for both balanced (line 278) and imbalanced (line 80).

current code line 278
y_hat_insample = Y_df[model_name].values.reshape(len(S_df), -1).astype(np.float32)
we should have
y_hat_insample = Y_hat_df[model_name].values.reshape(len(S_df), -1).astype(np.float32)
link to the code:
https://github.com/Nixtla/hierarchicalforecast/blob/0b853e511d43fd26463e906e4f2d39014c540239/hierarchicalforecast/core.py#L278C32-L278C32

Versions / Dependencies

0.4.1

Reproduction script

In colab example below if we add MinTrace(method='mint_shrink', nonnegative=True) to reconcilers it will generate error. I fixed it in local by changing Y_df to Y_hat_df
https://colab.research.google.com/github/nixtla/hierarchicalforecast/blob/main/nbs/examples/TourismSmall.ipynb

Issue Severity

Medium: It is a significant difficulty but I can work around it.

[jmoralez]

Hey @mnajaria, thanks for using hierarchicalforecast. That uses the in-sample predictions, so it's ok to be Y_df. I believe that example should compute the in-sample predictions as is done here, but @AzulGarza is the one who knows for sure.

[mnajaria]

@jmoralez Thanks for your reply and the link you shared.
I received error when I tried it with Y_df and changing it to Y_hat_df didn't generate errors. I will check again to see what the issue is.

[jmoralez]

The issue is that it'll look for the model columns in Y_df, so providing the in-sample predictions there would fix it. I'm not sure, however, if that's the expected behavior, let's wait for @AzulGarza.

[mnajaria]

If it is Y_hat_insample, shouldn't it be the prediction on train data? Here instead it uses the train Y_df instead of train Y_hat_df.