Why user_hist and user_count of val_data is not contained by val_data itself?

[pepsi2222]

the uh and uc of trn_data are added to trn_data, val_data and tst_data.
the uh and uc of val_data are added to tst_data, but why not add them to val_data itself?

The code is at the end of _build()

[XuHwang]

Because the user_hist passed to tst_data contains the interactions in val_data, we pass it to test data only because when evaluation on test data, we need to use interactions in val data.