music21.analysis.windowed¶
This module describes classes for performing windowed and overlapping windowed analysis.
The music21.analysis.windowed.WindowedAnalysis
provides a reusable framework for
systematic overlapping window analysis at the starting at the level of the quarter note
and moving to the size of an entire music21.stream.Stream
.
Modular analysis procedures inherit from music21.analysis.discrete.DiscreteAnalysis
.
The music21.analysis.discrete.KrumhanslSchmuckler
(for algorithmic key detection)
and music21.analysis.discrete.Ambitus
(for pitch range analysis) classes provide examples.
WindowedAnalysis¶

class
music21.analysis.windowed.
WindowedAnalysis
(streamObj, analysisProcessor)¶ Create a WindowedAnalysis object.
The provided analysisProcessor must provide a process() method that, when given a windowed Stream (a Measure) returns two element tuple containing (a) a data value (implementation dependent) and (b) a color code.
WindowedAnalysis
methods

WindowedAnalysis.
analyze
(windowSize, windowType='overlap')¶ Calls, for a given window size, an analysis method across all windows in the source Stream.
If windowType is “overlap”, windows above size 1 are always overlapped, so if a window of size 2 is used, windows 12, then 23, then 34 are compared. If a window of size 3 is used, windows 13, then 24, then 35 are compared.
Windows are assumed to be partitioned by
music21.stream.Measure
objects.Returns two lists for results, each equal in size to the length of minimum windows minus the window size plus one. If we have 20 1/4 windows, then the results lists will be of length 20 for window size 1, 19 for window size 2, 18 for window size 3, etc.
>>> s = corpus.parse('bach/bwv66.6') >>> p = analysis.discrete.Ambitus() >>> wa = analysis.windowed.WindowedAnalysis(s.flatten(), p) >>> len(wa._windowedStream) 36 >>> a, b = wa.analyze(1) >>> len(a), len(b) (36, 36)
>>> a, b = wa.analyze(4) >>> len(a), len(b) (33, 33)
>>> a, b = wa.analyze(1, windowType='noOverlap') >>> len(a), len(b) (37, 37)
>>> a, b = wa.analyze(4, windowType='noOverlap') >>> len(a), len(b) (10, 10)
>>> a, b = wa.analyze(1, windowType='adjacentAverage') >>> len(a), len(b) (36, 36)

WindowedAnalysis.
getMinimumWindowStream
(timeSignature='1/4')¶ Take the loaded stream and restructure it into measures of 1 quarter note duration.
>>> s = corpus.parse('bach/bwv324') >>> p = analysis.discrete.Ambitus()
Placing one part into analysis:
>>> wa = analysis.windowed.WindowedAnalysis(s.parts[0], p)
>>> post = wa.getMinimumWindowStream() >>> len(post.getElementsByClass('Measure')) 42 >>> post.getElementsByClass('Measure').first() <music21.stream.Measure 1 offset=0.0>
Time signature set to 1/4 time signature
>>> post.getElementsByClass('Measure').first().timeSignature <music21.meter.TimeSignature 1/4>
leaves one note in this measure
>>> len(post.getElementsByClass('Measure')[1].notes) 1
Placing a score with parts into analysis will automatically flatten the stream. So these two calls are equivalent:
>>> wa = analysis.windowed.WindowedAnalysis(s, p) >>> wa = analysis.windowed.WindowedAnalysis(s.flatten(), p)

WindowedAnalysis.
process
(minWindow: Optional[int] = 1, maxWindow: Optional[int] = 1, windowStepSize=1, windowType='overlap', includeTotalWindow=True)¶ Main method for windowed analysis across one or more window sizes.
Calls
analyze()
for the number of different window sizes to be analyzed.The minWindow and maxWindow set the range of window sizes in quarter lengths. The windowStepSize parameter determines the increment between these window sizes, in quarter lengths.
If minWindow or maxWindow is None, the largest window size available will be set.
If includeTotalWindow is True, the largest window size will always be added.
>>> s = corpus.parse('bach/bwv324') >>> ksAnalyzer = analysis.discrete.KrumhanslSchmuckler()
placing one part into analysis
>>> sopr = s.parts[0] >>> wa = analysis.windowed.WindowedAnalysis(sopr, ksAnalyzer) >>> solutions, colors, meta = wa.process(1, 1, includeTotalWindow=False) >>> len(solutions) # we only have one series of windows 1
>>> solutions, colors, meta = wa.process(1, 2, includeTotalWindow=False) >>> len(solutions) # we have two series of windows 2
>>> solutions[1] [(<music21.pitch.Pitch B>, 'major', 0.6844...), (<music21.pitch.Pitch B>, 'minor', 0.8308...), (<music21.pitch.Pitch D>, 'major', 0.6844...), (<music21.pitch.Pitch B>, 'minor', 0.8308...),...]
>>> colors[1] ['#ffb5ff', '#9b519b', '#ffd752', '#9b519b', ...]
>>> meta [{'windowSize': 1}, {'windowSize': 2}]
TestMockProcessor¶

class
music21.analysis.windowed.
TestMockProcessor
¶
TestMockProcessor
methods

TestMockProcessor.
process
(subStream)¶ Simply count the number of notes found