# -*- coding: utf-8 -*- # ------------------------------------------------------------------------------ # Name: metrical.py # Purpose: Tools for metrical analysis # # Authors: Christopher Ariza # Michael Scott Asato Cuthbert # # Copyright: Copyright © 2009-2012 Michael Scott Asato Cuthbert # License: BSD, see license.txt # ------------------------------------------------------------------------------ ''' Various tools and utilities for doing metrical or rhythmic analysis. See the chapter :ref:`User's Guide Chapter 14: Time Signatures ` for more information on defining metrical structures in music21. ''' from __future__ import annotations import copy import unittest from music21 import environment from music21 import stream environLocal = environment.Environment('analysis.metrical') def labelBeatDepth(streamIn): # noinspection PyShadowingNames r''' Modify a Stream in place by annotating metrical analysis symbols. This assumes that the Stream is already partitioned into Measures. >>> s = stream.Stream() >>> ts = meter.TimeSignature('4/4') >>> s.insert(0, ts) >>> n = note.Note(type='eighth') >>> s.repeatAppend(n, 8) >>> s.makeMeasures(inPlace=True) >>> post = analysis.metrical.labelBeatDepth(s) >>> sOut = [] >>> for n in s.flatten().notes: ... stars = "".join([l.text for l in n.lyrics]) ... sOut.append("{0:8s} {1}".format(n.beatStr, stars)) >>> print("\n".join(sOut)) 1 **** 1 1/2 * 2 ** 2 1/2 * 3 *** 3 1/2 * 4 ** 4 1/2 * ''' for m in streamIn.getElementsByClass(stream.Measure): # this will search contexts ts = m.getTimeSignatures(sortByCreationTime=False)[0] # need to make a copy otherwise the .beat/.beatStr values will be messed up (1/4 the normal) tsTemp = copy.deepcopy(ts) tsTemp.beatSequence.subdivideNestedHierarchy(depth=3) for n in m.notesAndRests: if hasattr(n, 'tie') and n.tie is not None: environLocal.printDebug(['note, tie', n, n.tie, n.tie.type]) if n.tie.type == 'stop': continue for unused_i in range(tsTemp.getBeatDepth(n.offset)): n.addLyric('*') return streamIn def thomassenMelodicAccent(streamIn: stream.Stream): # noinspection PyShadowingNames ''' Adds an attribute, 'melodicAccent' to each note's `.editorial` within a :class:`~music21.stream.Stream` object according to the method postulated in Joseph M. Thomassen, "Melodic accent: Experiments and a tentative model," ''Journal of the Acoustical Society of America'', Vol. 71, No. 6 (1982) pp. 1598-1605; with, Erratum, ''Journal of the Acoustical Society of America'', Vol. 73, No. 1 (1983) p.373, and in David Huron and Matthew Royal, "What is melodic accent? Converging evidence from musical practice." ''Music Perception'', Vol. 13, No. 4 (1996) pp. 489-516. Similar to the humdrum melac_ tool. .. _melac: https://www.humdrum.org/Humdrum/commands/melac.html Takes in a Stream of :class:`~music21.note.Note` objects (use `.flatten().notes` to get it, or better `.flatten().getElementsByClass(note.Note)` to filter out chords) and adds the attribute to each. Note that Huron and Royal's work suggests that melodic accent has a correlation with metrical accent only for solo works/passages; even treble passages do not have a strong correlation. (Gregorian chants were found to have a strong ''negative'' correlation between melodic accent and syllable onsets) Following Huron's lead, we assign a `melodicAccent` of 1.0 to the first note in a piece and take the accent marker of the first interval alone to the second note and of the last interval alone to be the accent of the last note. Example from Thomassen, figure 5: >>> s = converter.parse('tinynotation: 7/4 c4 c c d e d d') >>> analysis.metrical.thomassenMelodicAccent(s.flatten().notes) >>> for n in s.flatten().notes: ... (n.pitch.nameWithOctave, n.editorial.melodicAccent) ('C4', 1.0) ('C4', 0.0) ('C4', 0.0) ('D4', 0.33) ('E4', 0.5561) ('D4', 0.17) ('D4', 0.0) ''' # we use .ps instead of Intervals for speed, since # we just need perceived contours maxNotes = len(streamIn) - 1 p2Accent = 1.0 for i, n in enumerate(streamIn): if i == 0: n.editorial.melodicAccent = 1.0 continue elif i == maxNotes: n.editorial.melodicAccent = p2Accent continue lastPs = streamIn[i - 1].pitch.ps thisPs = n.pitch.ps nextPs = streamIn[i + 1].pitch.ps if lastPs == thisPs and thisPs == nextPs: thisAccent = 0.0 nextAccent = 0.0 elif lastPs != thisPs and thisPs == nextPs: thisAccent = 1.0 nextAccent = 0.0 elif lastPs == thisPs and thisPs != nextPs: thisAccent = 0.0 nextAccent = 1.0 elif lastPs < thisPs and thisPs > nextPs: thisAccent = 0.83 nextAccent = 0.17 elif lastPs > thisPs and thisPs < nextPs: thisAccent = 0.71 nextAccent = 0.29 elif lastPs < thisPs < nextPs: thisAccent = 0.33 nextAccent = 0.67 elif lastPs > thisPs > nextPs: thisAccent = 0.5 nextAccent = 0.5 else: # pragma: no cover # should not happen thisAccent = 0.0 nextAccent = 0.0 n.editorial.melodicAccent = thisAccent * p2Accent p2Accent = nextAccent # ------------------------------------------------------------------------------ class TestExternal(unittest.TestCase): show = True def testSingle(self): ''' Need to test direct meter creation w/o stream ''' from music21 import note from music21 import meter s = stream.Stream() ts = meter.TimeSignature('4/4') s.append(ts) n = note.Note() n.quarterLength = 1 s.repeatAppend(n, 4) n = note.Note() n.quarterLength = 0.5 s.repeatAppend(n, 8) s = s.makeMeasures() s = labelBeatDepth(s) if self.show: s.show() class Test(unittest.TestCase): pass # ------------------------------------------------------------------------------ # define presented order in documentation _DOC_ORDER = [labelBeatDepth] if __name__ == '__main__': import music21 music21.mainTest(Test) # , TestExternal)