[BurnP3+ Bug]: merge transformer uses all results scenarios if parent scenarios provided as dependencies

[katieb1]

Contact Details

No response

What happened?

Using the new merge transformer in the beta release (2.6.5), if I add multiple parent scenarios as dependencies to my new scenario that will use the merge transformer and some of those parent scenarios have multiple results scenarios, then BurnP3+ will try to merge ALL results scenarios. This was causing issues for me because one of the results scenarios did not have any output fire statistics, so was causing the merge to fail. I think generally with SyncroSim we try to only use the last results scenario (that did not fail) when the parent scenario is added as a dependency.

What component are you seeing the problem on?

R

Relevant log output

No response

Approvals Process

• Testing For Issue
• Merge

[shreeramsenthi]

Hey! I see your concern, but that was intended behaviour and already part of the workflow for a couple of folks. In particular it allows someone to set up a single scenario to sample and burn a smaller number of iterations and run it as many times as they need before merging and summarizing. This also allows users to tack on more runs without modifying the dependency structure.

Rather than using the parent as a dependency, you can also drag in specific result scenarios if you want finer control over what gets merged. You can also mix and match parent and result scenarios if that's helpful.

Lastly, I don't think there are many situations where users should merge from multiple parent scenarios. The biggest danger of the merge transformer is that it does not consider the sampled inputs at all, so it's entirely on the user to make sure all the scenarios represent independent samples from the same underlying distributions and inputs. This essentially means you should only ever be changing the iteration counts and proportions of extra ignitions and it's pretty easy to do accidentally do something else when you have multiple parent scenarios.