music21.bar

Object models of barlines, including repeat barlines.

Barline

class music21.bar.Barline(type=None, location=None)

A representation of a barline. Barlines are conventionally assigned to Measure objects using the leftBarline and rightBarline attributes.

>>> bl = bar.Barline('double')
>>> bl
<music21.bar.Barline type=double>

The type can also just be set via a keyword of “type”. Or if no type is specified, a regular barline is returned. Location can also be explicitly stored, but it’s not needed except for musicxml translation:

>>> bl2 = bar.Barline(type='dashed')
>>> bl2
<music21.bar.Barline type=dashed>
>>> bl3 = bar.Barline()
>>> bl3
<music21.bar.Barline type=regular>
>>> bl4 = bar.Barline(type='final', location='right')
>>> bl4
<music21.bar.Barline type=final>
>>> bl4.type
'final'

Note that the barline type ‘ticked’ only is displayed correctly in Finale and Finale Notepad.

N.B. for backwards compatibility reasons, currently Bar objects do not use the style.Style class since the phrase “style” was already used.

Barline bases

Barline read-only properties

Read-only properties inherited from Music21Object:

Read-only properties inherited from ProtoM21Object:

Barline read/write properties

Barline.type

Get and set the Barline type property.

>>> b = bar.Barline()
>>> b.type = 'tick'
>>> b.type
'tick'

Synonyms are given for some types, based on musicxml styles:

>>> b.type = 'light-light'
>>> b.type
'double'

Read/write properties inherited from Music21Object:

Barline methods

Barline.musicXMLBarStyle()

returns the musicxml style for the bar. most are the same as .type but “double” and “final” are different.

>>> b = bar.Barline('tick')
>>> b.musicXMLBarStyle()
'tick'

>>> b.type = 'double'
>>> b.musicXMLBarStyle()
'light-light'

>>> b.type = 'final'
>>> b.musicXMLBarStyle()
'light-heavy'

Changed in v.5.7 – was a property before.

Methods inherited from Music21Object:

Methods inherited from ProtoM21Object:

Barline instance variables

Instance variables inherited from Music21Object:

Repeat

class music21.bar.Repeat(direction='start', times=None)

A Repeat barline.

The direction parameter can be one of start or end. An end followed by a start should be encoded as two bar.Repeat signs.

>>> rep = bar.Repeat(direction='end', times=3)
>>> rep
<music21.bar.Repeat direction=end times=3>

To apply a repeat barline assign it to either the .leftBarline or .rightBarline attribute of a measure.

>>> m = stream.Measure()
>>> m.leftBarline = bar.Repeat(direction='start')
>>> m.rightBarline = bar.Repeat(direction='end')
>>> m.insert(0.0, meter.TimeSignature('4/4'))
>>> m.repeatAppend(note.Note('D--5'), 4)
>>> p = stream.Part()
>>> p.insert(0.0, m)
>>> p.show('text')
{0.0} <music21.stream.Measure 0 offset=0.0>
    {0.0} <music21.bar.Repeat direction=start>
    {0.0} <music21.meter.TimeSignature 4/4>
    {0.0} <music21.note.Note D-->
    {1.0} <music21.note.Note D-->
    {2.0} <music21.note.Note D-->
    {3.0} <music21.note.Note D-->
    {4.0} <music21.bar.Repeat direction=end>

The method expandRepeats() on a Part object expands the repeats, but does not update measure numbers

>>> q = p.expandRepeats()
>>> q.show('text')
{0.0} <music21.stream.Measure 0 offset=0.0>
    {0.0} <music21.bar.Barline type=double>
    {0.0} <music21.meter.TimeSignature 4/4>
    {0.0} <music21.note.Note D-->
    {1.0} <music21.note.Note D-->
    {2.0} <music21.note.Note D-->
    {3.0} <music21.note.Note D-->
    {4.0} <music21.bar.Barline type=double>
{4.0} <music21.stream.Measure 0a offset=4.0>
    {0.0} <music21.bar.Barline type=double>
    {0.0} <music21.meter.TimeSignature 4/4>
    {0.0} <music21.note.Note D-->
    {1.0} <music21.note.Note D-->
    {2.0} <music21.note.Note D-->
    {3.0} <music21.note.Note D-->
    {4.0} <music21.bar.Barline type=double>

Repeat bases

Repeat read-only properties

Read-only properties inherited from Music21Object:

Read-only properties inherited from ProtoM21Object:

Repeat read/write properties

Repeat.direction

Get or set the direction of this Repeat barline. Can be start or end.

TODO: show how changing direction changes type.

Repeat.times

Get or set the “times” property of this barline. This defines how many times the repeat happens. A standard repeat repeats 2 times; values equal to or greater than 0 are permitted. A repeat of 0 skips the repeated passage.

>>> lb = bar.Repeat(direction='start')
>>> rb = bar.Repeat(direction='end')

Only end expressions can have times:

>>> lb.times = 3
Traceback (most recent call last):
music21.bar.BarException: cannot set repeat times on a start Repeat

>>> rb.times = 3
>>> rb.times = -3
Traceback (most recent call last):
music21.bar.BarException: cannot set repeat times to a value less than zero: -3

Read/write properties inherited from Barline:

Read/write properties inherited from Music21Object:

Repeat methods

Repeat.getTextExpression(prefix='', postfix='x')

Return a configured TextExpressions object describing the repeat times. Append this to the stream for annotation of repeat times.

>>> rb = bar.Repeat(direction='end')
>>> rb.times = 3
>>> rb.getTextExpression()
<music21.expressions.TextExpression '3x'>

>>> rb.getTextExpression(prefix='repeat ', postfix=' times')
<music21.expressions.TextExpression 'repeat 3 t...'>

Methods inherited from Barline:

Methods inherited from Music21Object:

Methods inherited from ProtoM21Object:

Repeat instance variables

Instance variables inherited from Music21Object:

Functions

music21.bar.standardizeBarType(value)

Standardizes bar type names.

converts all names to lower case, None to ‘regular’, and ‘light-light’ to ‘double’ and ‘light-heavy’ to ‘final’, raises an error for unknown styles.

music21.bar.typeToMusicXMLBarStyle(value)

Convert a music21 barline name into the musicxml name – essentially just changes the names of ‘double’ and ‘final’ to ‘light-light’ and ‘light-heavy’

Does not do error checking to make sure it’s a valid name, since setting the style on a Barline object already does that.

>>> bar.typeToMusicXMLBarStyle('final')
'light-heavy'
>>> bar.typeToMusicXMLBarStyle('regular')
'regular'