fix peak per event plugin

[RoiFrankel]

Before you submit this PR: make sure to put all operations-related information in a wiki-note, a PR should be about code and is publicly accessible

What does the code in this PR do / what does it improve?

Fix the Bug of the mismatch between peaks['event_number'] and event['event_number'] given by peak_per_event plugin.
More details on the bug and his solution are at the following wiki note:
https://xe1t-wiki.lngs.infn.it/doku.php?id=xenon:xenonnt:analysis:analysts_overview_page:roi_frankel:Event_number_bug

Can you briefly describe how it works?

We start by sorting the indices of fully contained peaks. Then, we create a dictionary called 'mapping',
where keys represent event numbers in peak level data, and values represent event numbers in event level data.

The 'mapping' dictionary ensures that each event number at the peak level corresponds to the correct event
number at the event level.
We then use 'corrected_split_peaks_ind' to update the event numbers of
peaks based on the 'mapping' dictionary.
This process ensures that event numbers match between peaks and events.
The 'result['event_number']' array is updated with 'corrected_split_peaks_ind', ensuring that event numbers
in peaks are consistent with those in events, maintaining the original length and preserving -1 values for peaks
where event numbers are not applicable.

Can you give a minimal working example (or illustrate with a figure)?

An example could be found at the wiki note :
https://xe1t-wiki.lngs.infn.it/doku.php?id=xenon:xenonnt:analysis:analysts_overview_page:roi_frankel:Event_number_bug

Test with detailed example for bug and solution could be found at this notebook:
https://github.com/XENONnT/analysiscode/blob/master/peak_per_event_corrected/new_peak_per_event_plugin.ipynb

[coveralls]

coverage: 91.158% (+0.03%) from 91.125%
when pulling 1dadb67 on peak_per_event_bug_fix
into 189c09e on master.

[HenningSE]

Hi @RoiFrankel thanks for the PR. Right now you have a long explanation of the proposed changes as comments in the code. It is of course nice to explain changes, but I would propose to move these comments from the code to the description of the PR otherwise the code will get difficult to track as more and more comments would pile up at some point.

[RoiFrankel]

Hi @HenningSE I tried to fix it according to your suggestions, I hope this is now fine.

[yuema137]

Hi @RoiFrankel good catch and nice implementation! I went through your note and module in analysis code, which are quite clear. As you already have those checks in hand, can I ask you for another favor to add an unit test for this plugin, i.e. create a peak_per_event.py under straxen/tests/plugins?
Don't worry if you don't want to do it as it's not necessary.
Thanks a lot :)

The commit by me is just to remove the redundant # in the comment to resolve the error from pre-commit checking. Nothing changed functionally.

[RoiFrankel]

Hi @yuema137 thanks for your respond ! I will add the unit test for the plugin :)

[yuema137]

@RoiFrankel How's it going there? Don't worry if you don't have time to add the test. We can merge this PR without it.

[yuema137]

@dachengx we can go ahead to merge this PR. I talked to Roi offline and we decided to add the test in the future.