Let `makeTies()` iterate over parts

[TimFelixBeyer]

music21 version
master

Problem summary
makeTies throws StreamException: cannot process a stream without measures on score with measures.

Steps to reproduce

from music21 import stream, note, meter, tie

s = stream.Score(id='mainScore')
p0 = stream.Part(id='part0')

m01 = stream.Measure(number=1)
m01.append(meter.TimeSignature('4/4'))
d1 = note.Note('D', type="half", dots=1)
c1 = note.Note('C', type="quarter")
c1.tie = tie.Tie("start")
m01.append([d1, c1])
m02 = stream.Measure(number=2)
c2 = note.Note('C', type="quarter")
c2.tie = tie.Tie("stop")
c3 = note.Note("D", type="half")
m02.append([c2, c3])
p0.append([m01, m02])

s.insert(0, p0)
s.show("text")  # just to verify that there are measures in the score 
s = s.stripTies()
# s = s.makeMeasures()  # does not help
s = s.makeTies()

More information
Related to #1557

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3
Your example is a score that has had stripTies() run on it, yielding an overfilled first measure and an underfilled second measure. I think I would expect that making rests on that would fill the second measure.

If you want to display the stripped ties score (are you sure you want to display that?) then you could makeTies() on it first, which restores the output I think you're expecting.

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Originally posted by @jacobtylerwalls in #1557 (comment)

[mscuthbert]

I've never really worked with stripTies() except in the context of a flatten()'d stream, so I'm not surprised this is a problem.

[TimFelixBeyer]

Just found out that it also fails without stripTies():

from music21 import stream, note, meter, tie

s = stream.Score(id='mainScore')
p0 = stream.Part(id='part0')

m01 = stream.Measure(number=1)
m01.append(meter.TimeSignature('4/4'))
d1 = note.Note('D', type="half", dots=1)
c1 = note.Note('C', type="quarter")
c1.tie = tie.Tie("start")
m01.append([d1, c1])
m02 = stream.Measure(number=2)
c2 = note.Note('C', type="quarter")
c2.tie = tie.Tie("stop")
c3 = note.Note("D", type="half")
m02.append([c2, c3])
p0.append([m01, m02])

s.insert(0, p0)
s.show("text")  # just to verify that there are measures in the score 
# s = s.makeMeasures()  # does not help
s = s.makeTies()

This also fails when called on the example score from here (makeMeasures does not help there either): https://web.mit.edu/music21/doc/usersGuide/usersGuide_06_stream2.html

[jacobtylerwalls]

When the exception message says "with/without", it means "directly containing", not "recursively containing". Your score doesn't directly contain measures; the parts do.

Try:

>>> for p in s.parts:
...   p.makeTies(inPlace=True)
...

Leaving the issue open for now to discuss the possibility of adding the trivially easy enhancement to iterate over parts of a score automatically.

[TimFelixBeyer]

I think that makeTies should be the conceptual opposite to stripTies, which itself already iterates over parts and voices if required

music21/music21/stream/base.py

Lines 7257 to 7278 in 42534a3

	if returnObj.hasPartLikeStreams():
	# part-like does not necessarily mean that the next level down is a stream.Part
	# object or that this is a stream.Score object, so do not substitute
	# returnObj.parts for this...
	for p in returnObj.getElementsByClass(Stream):
	# already copied if necessary; edit in place
	p.stripTies(inPlace=True, matchByPitch=matchByPitch)
	if not inPlace:
	return returnObj
	else:
	return # exit
	if returnObj.hasVoices():
	for v in returnObj.voices:
	# already copied if necessary; edit in place
	v.stripTies(inPlace=True, matchByPitch=matchByPitch)
	if not inPlace:
	return returnObj
	else:
	return # exit
	# need to just get .notesAndRests with a nonzero duration,

LMK if that's something I should prepare a PR for or whether further discussion is required!

[jacobtylerwalls]

I'd welcome such a PR, it brings that method into alignment with other related stream methods without significantly increasing the API footprint. Many thanks!

[mscuthbert]

I'm okay with having it in, but I think it is an extremely complex undertaking for an early PR to the project. Having makeTies iterate over parts (and for Opus objects, also Scores) is a more managable start.

[jacobtylerwalls]

Having makeTies iterate over parts (and for Opus objects, also Scores) is a more managable start.

That's all I was referring to. @TimFelixBeyer were you referring to something else?

[mscuthbert]

I thought he was referring to having makeTies() more fully undo stripTies() and also separate chords into multiple voices. I must have misread. Yes, having them iterate over parts is a very welcome and manageable first mergable PR.