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music21.abcFormat

Functions

music21.abcFormat.mergeLeadingMetaData(barHandlers)

Given a list of ABCHandlerBar objects, return a list of ABCHandlerBar objects where leading metadata is merged, if possible, with the bar data following.

This consolidates all metadata in bar-like entities.

ABCFile

class music21.abcFormat.ABCFile

ABC File or String access

ABCFile methods

ABCFile.close()
ABCFile.extractReferenceNumber(strSrc, number)

Extract a single reference number from many defined in a file. This permits loading a single work from a collection/opus without parsing the entire file.

ABCFile.open(filename)

Open a file for reading

ABCFile.openFileLike(fileLike)

Assign a file-like object, such as those provided by StringIO, as an open file object.

>>> from io import StringIO
>>> fileLikeOpen = StringIO()
ABCFile.read(number=None)

Read a file. Note that this calls readstring, which processes all tokens.

If number is given, a work number will be extracted if possible.

ABCFile.readstr(strSrc, number=None)

Read a string and process all Tokens. Returns a ABCHandler instance.

ABCHandler

class music21.abcFormat.ABCHandler

ABCHandler read/write properties

ABCHandler.tokens

Get or set tokens for this Handler

ABCHandler methods

ABCHandler.barlineTokenFilter(token)

Some single barline tokens are better replaced with two tokens. This method, given a token, returns a list of tokens. If there is no change necessary, the provided token will be returned in the list.

>>> abch = abcFormat.ABCHandler()
>>> abch.barlineTokenFilter('::')
[<music21.abcFormat.ABCBar ':|'>, <music21.abcFormat.ABCBar '|:'>]
ABCHandler.definesMeasures()

Returns True if this token structure defines Measures in a normal Measure form. Otherwise False

>>> abcStr = 'M:6/8\nL:1/8\nK:G\nV:1 name="Whistle" snm="wh"\nB3 A3 | G6 | B3 A3 | G6 ||\nV:2 name="violin" snm="v"\nBdB AcA | GAG D3 | BdB AcA | GAG D6 ||\nV:3 name="Bass" snm="b" clef=bass\nD3 D3 | D6 | D3 D3 | D6 ||'
>>> ah = abcFormat.ABCHandler()
>>> junk = ah.process(abcStr)
>>> ah.definesMeasures()
True
>>> abcStr = 'M:6/8\nL:1/8\nK:G\nB3 A3 G6 B3 A3 G6'
>>> ah = abcFormat.ABCHandler()
>>> junk = ah.process(abcStr)
>>> ah.definesMeasures()
False
ABCHandler.definesReferenceNumbers()

Return True if this token structure defines more than 1 reference number, usually implying multiple pieces encoded in one file.

>>> abcStr = 'X:5\nM:6/8\nL:1/8\nK:G\nB3 A3 | G6 | B3 A3 | G6 ||'
>>> ah = abcFormat.ABCHandler()
>>> junk = ah.process(abcStr)
>>> ah.definesReferenceNumbers() # only one returns False
False 
>>> abcStr = 'X:5\nM:6/8\nL:1/8\nK:G\nB3 A3 | G6 | B3 A3 | G6 ||\n'
>>> abcStr += 'X:6\nM:6/8\nL:1/8\nK:G\nB3 A3 | G6 | B3 A3 | G6 ||'
>>> ah = abcFormat.ABCHandler()
>>> junk = ah.process(abcStr)
>>> ah.definesReferenceNumbers() # two tokens so returns True
True 
ABCHandler.getReferenceNumber()

If tokens are processed, get the first reference number defined.

>>> abcStr = 'X:5\nM:6/8\nL:1/8\nK:G\nB3 A3 | G6 | B3 A3 | G6 ||'
>>> ah = abcFormat.ABCHandler()
>>> junk = ah.process(abcStr)
>>> ah.getReferenceNumber()
'5'
ABCHandler.getTitle()

Get the first title tag. Used for testing.

Requires tokens to have been processed.

ABCHandler.hasNotes()

If tokens are processed, return True if ABCNote or ABCChord classes are defined

>>> abcStr = 'M:6/8\nL:1/8\nK:G\n' 
>>> ah1 = abcFormat.ABCHandler()
>>> junk = ah1.process(abcStr)
>>> ah1.hasNotes()
False
>>> abcStr = 'M:6/8\nL:1/8\nK:G\nc1D2' 
>>> ah2 = abcFormat.ABCHandler()
>>> junk = ah2.process(abcStr)
>>> ah2.hasNotes()
True
ABCHandler.process(strSrc)
ABCHandler.splitByMeasure()

Divide a token list by Measures, also defining start and end bars of each Measure.

If a component does not have notes, leave as an empty bar. This is often done with leading metadata.

Returns a list of ABCHandlerBar instances. The first usually defines only Metadata

TODO: Test and examples

ABCHandler.splitByReferenceNumber()

Split tokens by reference numbers.

Returns a dictionary of ABCHandler instances, where the reference number is used to access the music. If no reference numbers are defined, the tune is available under the dictionary entry None.

>>> abcStr = 'X:5\nM:6/8\nL:1/8\nK:G\nB3 A3 | G6 | B3 A3 | G6 ||'
>>> abcStr += 'X:6\nM:6/8\nL:1/8\nK:G\nB3 A3 | G6 | B3 A3 | G6 ||'
>>> ah = abcFormat.ABCHandler()
>>> junk = ah.process(abcStr)
>>> len(ah)
28
>>> ahDict = ah.splitByReferenceNumber()
>>> 5 in ahDict
True
>>> 6 in ahDict
True
>>> 7 in ahDict
False
>>> len(ahDict[5].tokens)
14
ABCHandler.splitByVoice()

Given a processed token list, look for voices. If voices exist, split into parts: common metadata, then next voice, next voice, etc.

Each part is returned as a ABCHandler instance.

>>> abcStr = 'M:6/8\nL:1/8\nK:G\nV:1 name="Whistle" snm="wh"\nB3 A3 | G6 | B3 A3 | G6 ||\nV:2 name="violin" snm="v"\nBdB AcA | GAG D3 | BdB AcA | GAG D6 ||\nV:3 name="Bass" snm="b" clef=bass\nD3 D3 | D6 | D3 D3 | D6 ||'
>>> ah = abcFormat.ABCHandler()
>>> junk = ah.process(abcStr)
>>> tokenColls = ah.splitByVoice()
>>> tokenColls[0]
<music21.abcFormat.ABCHandler object at 0x...>
>>> [t.src for t in tokenColls[0].tokens] # common headers are first
['M:6/8', 'L:1/8', 'K:G']
>>> # then each voice
>>> [t.src for t in tokenColls[1].tokens] 
['V:1 name="Whistle" snm="wh"', 'B3', 'A3', '|', 'G6', '|', 'B3', 'A3', '|', 'G6', '||']
>>> [t.src for t in tokenColls[2].tokens] 
['V:2 name="violin" snm="v"', 'B', 'd', 'B', 'A', 'c', 'A', '|', 'G', 'A', 'G', 'D3', '|', 'B', 'd', 'B', 'A', 'c', 'A', '|', 'G', 'A', 'G', 'D6', '||']
>>> [t.src for t in tokenColls[3].tokens] 
['V:3 name="Bass" snm="b" clef=bass', 'D3', 'D3', '|', 'D6', '|', 'D3', 'D3', '|', 'D6', '||']

Then later the metadata can be merged at the start of each voice...

>>> mergedTokens = tokenColls[0] + tokenColls[1]
>>> mergedTokens
<music21.abcFormat.ABCHandler object at 0x...>
>>> [t.src for t in mergedTokens.tokens] 
['M:6/8', 'L:1/8', 'K:G', 'V:1 name="Whistle" snm="wh"', 'B3', 'A3', '|', 'G6', '|', 'B3', 'A3', '|', 'G6', '||']
ABCHandler.tokenProcess()

Process all token objects. First, calls preParse(), then does context assignments, then calls parse().

ABCHandler.tokenize(strSrc)

Walk the abc string, creating ABC objects along the way.

This may be called separately from process(), in the case that pre/post parse processing is not needed.

>>> abch = abcFormat.ABCHandler()
>>> abch._tokens
[]
>>> abch.tokenize('X: 1')
>>> abch._tokens
[<music21.abcFormat.ABCMetadata 'X: 1'>]

ABCHandlerBar

class music21.abcFormat.ABCHandlerBar

A Handler specialized for storing bars. All left and right bars are collected and assigned to attributes.

ABCHandlerBar bases

ABCHandlerBar read/write properties

Read/write properties inherited from ABCHandler:

ABCHandlerBar methods

Methods inherited from ABCHandler:

ABCAccent

class music21.abcFormat.ABCAccent(src='')

ABCAccent tokens “K” precede a note or chord; they are a property of that note/chord. These appear as “>” in the output.

ABCAccent bases

ABCAccent methods

Methods inherited from ABCToken:

ABCBar

class music21.abcFormat.ABCBar(src)

ABCBar bases

ABCBar methods

ABCBar.getBarObject()

Return a music21 bar object

>>> ab = abcFormat.ABCBar('|:')
>>> ab.parse()
>>> post = ab.getBarObject()
ABCBar.isRegular()

Return True if this is a regular, single, light bar line.

>>> ab = abcFormat.ABCBar('|')
>>> ab.parse()
>>> ab.isRegular()
True
ABCBar.isRepeat()
ABCBar.isRepeatBracket()

Return true if this defines a repeat bracket for an alternate ending

>>> ab = abcFormat.ABCBar('[2')
>>> ab.parse()
>>> ab.isRepeat()
False
>>> ab.isRepeatBracket()
2
ABCBar.parse()

Assign the bar-type based on the source string.

>>> ab = abcFormat.ABCBar('|')
>>> ab.parse()
>>> ab
<music21.abcFormat.ABCBar '|'>
>>> ab.barType
'barline'
>>> ab.barStyle
'regular'
>>> ab = abcFormat.ABCBar('||')
>>> ab.parse()
>>> ab.barType
'barline'
>>> ab.barStyle
'light-light'
>>> ab = abcFormat.ABCBar('|:')
>>> ab.parse()
>>> ab.barType
'repeat'
>>> ab.barStyle
'heavy-light'
>>> ab.repeatForm
'start'

Methods inherited from ABCToken:

ABCBrokenRhythmMarker

class music21.abcFormat.ABCBrokenRhythmMarker(src)

ABCBrokenRhythmMarker bases

ABCBrokenRhythmMarker methods

ABCBrokenRhythmMarker.preParse()

Called before context adjustments: need to have access to data

>>> abrm = abcFormat.ABCBrokenRhythmMarker('>>>')
>>> abrm.preParse()
>>> abrm.data
'>>>'

Methods inherited from ABCToken:

ABCChord

class music21.abcFormat.ABCChord(src)

A representation of an ABC Chord, which contains within its delimiters individual notes.

A subclass of ABCNote.

ABCChord bases

ABCChord methods

ABCChord.parse(forceKeySignature=None, forceDefaultQuarterLength=None)

Methods inherited from ABCToken:

ABCCrescStart

class music21.abcFormat.ABCCrescStart(src)

ABCCrescStart tokens always precede the notes in a crescendo. These tokens coincide with the string ”!crescendo(”; the closing string ”!crescendo)” counts as an ABCParenStop.

ABCCrescStart bases

ABCCrescStart methods

ABCCrescStart.fillCresc()

Methods inherited from ABCToken:

ABCDimStart

class music21.abcFormat.ABCDimStart(src='')

ABCDimStart tokens always precede the notes in a diminuendo. They function identically to ABCCrescStart tokens.

ABCDimStart bases

ABCDimStart methods

ABCDimStart.fillDim()

Methods inherited from ABCToken:

ABCDownbow

class music21.abcFormat.ABCDownbow(src='')

ABCStaccato tokens ”.” precede a note or chord; they are a property of that note/chord.

ABCDownbow bases

ABCDownbow methods

Methods inherited from ABCToken:

ABCGraceStart

class music21.abcFormat.ABCGraceStart(src='')

ABCGraceStart bases

ABCGraceStart methods

Methods inherited from ABCToken:

ABCGraceStop

class music21.abcFormat.ABCGraceStop(src='')

ABCGraceStop bases

ABCGraceStop methods

Methods inherited from ABCToken:

ABCMetadata

class music21.abcFormat.ABCMetadata(src='')

ABCMetadata bases

ABCMetadata methods

ABCMetadata.getClefObject()

Extract any clef parameters stored in the key metadata token. Assume that a clef definition suggests a transposition. Return both the Clef and the transposition.

Returns a two-element tuple of clefObj and transposition in semitones

>>> am = abcFormat.ABCMetadata('K:Eb Lydian bass')
>>> am.preParse()
>>> am.getClefObject()
(<music21.clef.BassClef>, -24)
ABCMetadata.getDefaultQuarterLength()

If there is a quarter length representation available, return it as a floating point value

>>> am = abcFormat.ABCMetadata('L:1/2')
>>> am.preParse()
>>> am.getDefaultQuarterLength()
2.0
>>> am = abcFormat.ABCMetadata('L:1/8')
>>> am.preParse()
>>> am.getDefaultQuarterLength()
0.5
>>> am = abcFormat.ABCMetadata('M:C|')
>>> am.preParse()
>>> am.getDefaultQuarterLength()
0.5
>>> am = abcFormat.ABCMetadata('M:2/4')
>>> am.preParse()
>>> am.getDefaultQuarterLength()
0.25
>>> am = abcFormat.ABCMetadata('M:6/8')
>>> am.preParse()
>>> am.getDefaultQuarterLength()
0.5
ABCMetadata.getKeySignatureObject()

Return a music21 KeySignature object for this metadata tag.

>>> am = abcFormat.ABCMetadata('K:G')
>>> am.preParse()
>>> ks = am.getKeySignatureObject()
>>> ks
<music21.key.KeySignature of 1 sharp>
ABCMetadata.getMetronomeMarkObject()

Extract any tempo parameters stored in a tempo metadata token.

>>> am = abcFormat.ABCMetadata('Q: "Allegro" 1/4=120')
>>> am.preParse()
>>> am.getMetronomeMarkObject()
<music21.tempo.MetronomeMark Allegro Quarter=120.0>
>>> am = abcFormat.ABCMetadata('Q: 3/8=50 "Slowly"')
>>> am.preParse()
>>> am.getMetronomeMarkObject()
<music21.tempo.MetronomeMark Slowly Dotted Quarter=50.0>
>>> am = abcFormat.ABCMetadata('Q:1/2=120')
>>> am.preParse()
>>> am.getMetronomeMarkObject()
<music21.tempo.MetronomeMark animato Half=120.0>
>>> am = abcFormat.ABCMetadata('Q:1/4 3/8 1/4 3/8=40')
>>> am.preParse()
>>> am.getMetronomeMarkObject()
<music21.tempo.MetronomeMark grave Whole tied to Quarter (5.0 total QL)=40.0>
>>> am = abcFormat.ABCMetadata('Q:90')
>>> am.preParse()
>>> am.getMetronomeMarkObject()
<music21.tempo.MetronomeMark maestoso Quarter=90.0>
ABCMetadata.getTimeSignatureObject()

Return a music21 TimeSignature object for this metadata tag.

>>> am = abcFormat.ABCMetadata('M:2/2')
>>> am.preParse()
>>> ts = am.getTimeSignatureObject()
>>> ts
<music21.meter.TimeSignature 2/2>
ABCMetadata.isComposer()

Returns True if the tag is “C” for composer, False otherwise.

ABCMetadata.isDefaultNoteLength()

Returns True if the tag is “L”, False otherwise.

ABCMetadata.isKey()

Returns True if the tag is “K”, False otherwise. Note that in some cases a Key will encode clef information.

ABCMetadata.isMeter()

Returns True if the tag is “M” for meter, False otherwise.

ABCMetadata.isOrigin()

Returns True if the tag is “O” for origin, False otherwise. This value is set in the Metadata localOfComposition of field.

ABCMetadata.isReferenceNumber()

Returns True if the tag is “X”, False otherwise.

>>> x = abcFormat.ABCMetadata('X:5')
>>> x.preParse()
>>> x.tag
'X'
>>> x.isReferenceNumber()
True
ABCMetadata.isTempo()

Returns True if the tag is “Q” for tempo, False otherwise.

ABCMetadata.isTitle()

Returns True if the tag is “T” for title, False otherwise.

ABCMetadata.isVoice()

Returns True if the tag is “V”, False otherwise.

ABCMetadata.parse()
ABCMetadata.preParse()

Called before contextual adjustments and needs to have access to data. Divides a token into .tag (a single capital letter or w) and .data representations.

>>> x = abcFormat.ABCMetadata('T:tagData')
>>> x.preParse()
>>> x.tag
'T'
>>> x.data
'tagData'

Methods inherited from ABCToken:

ABCNote

class music21.abcFormat.ABCNote(src='')

A model of an ABCNote.

General usage requires multi-pass processing. After being tokenized, each ABCNote needs a number of attributes updates. Attributes to be updated after tokenizing, and based on the linear sequence of tokens: inBar, inBeam (not used), inGrace, activeDefaultQuarterLength, brokenRhythmMarker, and activeKeySignature.

The chordSymbols list stores one or more chord symbols (ABC calls these guitar chords) associated with this note. This attribute is updated when parse() is called.

ABCNote bases

ABCNote methods

ABCNote.parse(forceDefaultQuarterLength=None, forceKeySignature=None)

Methods inherited from ABCToken:

ABCParenStop

class music21.abcFormat.ABCParenStop(src)

A general parenthesis stop; comes at the end of a tuplet, slur, or dynamic marking.

ABCParenStop bases

ABCParenStop methods

Methods inherited from ABCToken:

ABCSlurStart

class music21.abcFormat.ABCSlurStart(src)

ABCSlurStart tokens always precede the notes in a slur. For nested slurs, each open parenthesis gets its own token.

ABCSlurStart bases

ABCSlurStart methods

ABCSlurStart.fillSlur()

Methods inherited from ABCToken:

ABCStaccato

class music21.abcFormat.ABCStaccato(src='')

ABCStaccato tokens ”.” precede a note or chord; they are a property of that note/chord.

ABCStaccato bases

ABCStaccato methods

Methods inherited from ABCToken:

ABCStraccent

class music21.abcFormat.ABCStraccent(src='')

ABCStraccent tokens “k” precede a note or chord; they are a property of that note/chord. These appear as “^” in the output.

ABCStraccent bases

ABCStraccent methods

Methods inherited from ABCToken:

ABCTenuto

class music21.abcFormat.ABCTenuto(src='')

ABCTenuto tokens “M” precede a note or chord; they are a property of that note/chord.

ABCTenuto bases

ABCTenuto methods

Methods inherited from ABCToken:

ABCTie

class music21.abcFormat.ABCTie(src)

Handles instances of ties ‘-‘ between notes in an ABC score. Ties are treated as an attribute of the note before the ‘-‘; the note after is marked as the end of the tie.

ABCTie bases

ABCTie methods

Methods inherited from ABCToken:

ABCToken

class music21.abcFormat.ABCToken(src='')

ABC processing works with a multi-pass procedure. The first pass breaks the data stream into a list of ABCToken objects. ABCToken objects are specialized in subclasses.

The multi-pass procedure is conducted by an ABCHandler object. The ABCHandler.tokenize() method breaks the data stream into ABCToken objects. The tokenProcess() method first calls the preParse() method on each token, then does contextual adjustments to all tokens, then calls parse() on all tokens.

The source ABC string itself is stored in self.src

ABCToken methods

ABCToken.parse()

Dummy method that reads self.src and loads attributes. It is called after contextual adjustments.

It is designed to be subclassed or overridden.

ABCToken.preParse()

Dummy method that is called before contextual adjustments. Designed to be subclassed or overridden.

ABCToken.stripComment(strSrc)

removes ABC-style comments from a string:

>>> ao = abcFormat.ABCToken()
>>> ao.stripComment('asdf')
'asdf'
>>> ao.stripComment('asdf%234')
'asdf'
>>> ao.stripComment('asdf  %     234')
'asdf  '        
>>> ao.stripComment('[ceg]% this chord appears 50% more often than other chords do')
'[ceg]'

ABCTuplet

class music21.abcFormat.ABCTuplet(src)

ABCTuplet tokens always precede the notes they describe.

In ABCHandler.tokenProcess(), rhythms are adjusted.

ABCTuplet bases

ABCTuplet methods

ABCTuplet.updateNoteCount(durationActual=None, durationNormal=None)

Update the note count of notes that are affected by this tuplet.

ABCTuplet.updateRatio(keySignatureObj=None)

Cannot be called until local meter context is established.

>>> at = abcFormat.ABCTuplet('(3')
>>> at.updateRatio()
>>> at.numberNotesActual, at.numberNotesNormal
(3, 2)
>>> at = abcFormat.ABCTuplet('(5')
>>> at.updateRatio()
>>> at.numberNotesActual, at.numberNotesNormal
(5, 2)
>>> at = abcFormat.ABCTuplet('(5')
>>> at.updateRatio(meter.TimeSignature('6/8'))
>>> at.numberNotesActual, at.numberNotesNormal
(5, 3)

Methods inherited from ABCToken:

ABCUpbow

class music21.abcFormat.ABCUpbow(src='')

ABCStaccato tokens ”.” precede a note or chord; they are a property of that note/chord.

ABCUpbow bases

ABCUpbow methods

Methods inherited from ABCToken: