Verse segmentation fix

[laura-burdick-sil]

Previously, the verse segmentation algorithm was crashing when there was a passage that was only a single verse. This fixes that behavior.

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This change is 

[Enkidu93]

@Enkidu93 reviewed 1 of 1 files at r1, all commit messages.
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[laura-burdick-sil]

I've also added some code to output the resulting verses in vref format (so that they can easily be fed directly into NLLB). @Enkidu93, would you also be able to review this code? Thank you!

[Enkidu93]

Sure! This looks good.

My one concern is versification: It looks like the source and target verses are created without having a versification specified. In both cases, the versification will default to the English versification (luckily the same!). The vref.txt format, I believe, follows the Original versification.

I think we could address handling different versifications properly in a separate issue (unless you'd like to just do it now). For the time being could you confirm that there's a mismatch and if so just change the versification of the verse refs in verse_map to Original before str()ing them so the lookup will be apples-to-apples?

@Enkidu93 reviewed all commit messages.
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[laura-burdick-sil]

That's a good point, thanks for catching that! I've been digging into the code around versification, but I've never worked with it before, so I'm not sure that I've implemented this correctly.

In Paratext, the source project is marked as having a versification of 4 (would that be English versification?). I'm not sure what the versification of the target project is, since I don't have access to their Paratext project.

[Enkidu93]

Versification is a hairy thing 😬 😁 . 4 would be English, yes. Yeah, it seems like we just didn't think of this before. Probably not making much difference at the moment but we'll definitely want to address this as we move to a more established pipeline.

This works well, but I put in a comment for consideration!

@Enkidu93 reviewed all commit messages.
Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @benjaminking and @laura-burdick-sil)

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silnlp/alignment/segment_verses.py line 729 at r3 (raw file):

        for trg_passage in trg_segmented_passages:
            for verse in trg_passage.verses:
                verse.reference.change_versification(ORIGINAL_VERSIFICATION)

You might consider using VerseRef.to_versification which doesn't mutate the original reference and call it while iterating below. Besides saving a few lines, it would guarantee that steps after this step which may access those verse references will access the unchanged references.

[laura-burdick-sil]

Thanks for the comment - that's a good suggestion! I'll add an issue about addressing this versification issue more thoroughly at some point.