General Score Unfolding

[sildater]

This is the text of the PR that added segments and variable unfolding to partitura. It is copied here for future reference.

This PR contains the following new things in partitura.score.py:

• class Segment(TimedObject): a segment of a part between two time points that are relevant to the repetition structure

  • add_segments(part): a function adding segments to a part based on existing TimedObjects: Repeat, Ending, DaCapo, DalSegno, Segno, AlCoda, Coda, Fine
  • get_segments(part): returns a dict of segments indexed by segment ID
  • pretty_segments(part): creates a pretty string describing the segments of a part

• class Path: a Path object encodes a sequence of segments and utility needed to extend that sequence, if it hasn't reached an end of the part.

  • unfold_paths(*args): recursively unfold and multiply a Path into all possible Paths and store these in a list
  • get_paths(part, *args): call unfold_paths with the starting segment Path and return the resulting paths as parametrized (for options, see below)
  • new_part_from_path(*args): create a new part from a Path
  • new_scorevariant_from_path(*args): create a new ScoreVariant from a Path

• Updated functions from which now use the new unfolding:

  • iter_unfolded_parts(*args): iterator over all unfolded parts
  • unfolded_part_maximal(*args): returns the longest unfolded part
  • unfolded_part_alignment(*args): returns the unfolded part that best fits the note IDs in an alignment
  • make_score_variants(*args): creates a list of ScoreVariant objects

Why?

Theses changes solve limit cases of unfolding/segmentation:

• Volta brackets with >2 endings are supported
• Nested repeats are supported
• Other navigation marks (segno, coda, capo, fine) are supported

Additionally, the changes make the following possible:

• get all unfoldings with some specific constraints:
  • all!
  • the longest!
  • the longest without repeats after a jump mark (dal segno, al cado, da capo)
  • all without repeats after a jump mark (dal segno, al cado, da capo)
  • the shortest
• create any unfolding:
  • pick any segment(s) you like from the list of segments (print(partitura.score.pretty_segments(part)) for an overview)
  • add them to a path p = Path(["C","K","&",...], segments)
  • create a new part from this path new_part = new_part_from_path(p, part)
• get informative strings about segments and paths:
  • as above: print(partitura.score.pretty_segments(part))
  • for paths use print(path) or print(path.pretty())

How?

The Segments add information about the structure and the possible jumps from every segment to the part.
The Path parses this tree of possible unfoldings (with constraints, if desired).
The ScoreVariant creates a variant of the score based on the list of of segment IDs stored (or possibly computed) in a Path.

Other Bits and Fixes:

• load_musicxml: correct parsing of location attribute of barline tag
• load_musicxml: correct parsing of navigation markers (Da Capo, Al Segno, Segno, Al Coda, Coda, Fine)
• score.py: TimedObject subclasses for navigation markers
• ScoreVariant.create_variant_part(): Ignore the following score elements for the new part: Repeat, Ending, ToCoda, DaCapo, DalSegno, Segment, Page, System
• ScoreVariant.create_variant_part(): Check for previous clefs before adding new clef element
• modified the unfolding unittest and added a new more complex test for unfolding with jumps and three Volta brackets
• added part.measure_number_maphere
• added test for part.measure_number_map