ly.pitch package

Module contents

Pitch manipulation.

class ly.pitch.LanguageName[source]

Bases: ly.lex._token.Token

A Token that denotes a language name.

class ly.pitch.Pitch(note=0, alter=0, octave=0, accidental=u'', octavecheck=None)[source]

Bases: object

A pitch with note, alter and octave attributes.

Attributes may be manipulated directly.

classmethod c0()[source]

Returns a pitch c.

classmethod c1()[source]

Returns a pitch c’.

copy()[source]

Returns a new instance with our attributes.

classmethod f0()[source]

Return a pitch f.

makeAbsolute(lastPitch)[source]

Makes ourselves absolute, i.e. sets our octave from lastPitch.

makeRelative(lastPitch)[source]

Makes ourselves relative, i.e. changes our octave from lastPitch.

output(language=u'nederlands')[source]

Returns our string representation.

class ly.pitch.PitchIterator(source, language=u'nederlands')[source]

Bases: object

Iterate over notes or pitches in a source.

pitches()[source]

Yields all tokens, but collects Note and Octave tokens.

When a Note is encountered, also reads octave and octave check and then a Pitch is yielded instead of the tokens.

position(t)[source]

Returns the cursor position for the given token or Pitch.

read(token)[source]

Reads the token and returns (note, alter) or None.

setLanguage(lang)[source]

Changes the pitch name language to use.

Called internally when language or include tokens are encountered with a valid language name/file.

Sets the language attribute to the language name and the read attribute to an instance of ly.pitch.PitchReader.

tokens()[source]

Yield all the tokens from the source, following the language.

write(pitch, language=None)[source]

Output a changed Pitch.

The Pitch is written in the Source’s document.

To use this method reliably, you must instantiate the PitchIterator with a ly.document.Source that has tokens_with_position set to True.

exception ly.pitch.PitchNameNotAvailable(language)[source]

Bases: exceptions.Exception

Exception raised when there is no name for a pitch.

Can occur when translating pitch names, if the target language e.g. does not have quarter-tone names.

class ly.pitch.PitchReader(names, accs, replacements=())[source]

Bases: object

class ly.pitch.PitchWriter(names, accs, replacements=())[source]

Bases: object

language = u'unknown'
ly.pitch.octaveToNum(octave)[source]

Converts string octave to an integer:

“” -> 0 ; ”,” -> -1 ; “’‘’” -> 3 ; etc.

ly.pitch.octaveToString(octave)[source]

Converts numeric octave to a string with apostrophes or commas.

0 -> “” ; 1 -> “’” ; -1 -> ”,” ; etc.

ly.pitch.pitchReader(language)[source]

Returns a PitchReader for the specified language.

ly.pitch.pitchWriter(language)[source]

Returns a PitchWriter for the specified language.

Submodules

ly.pitch.abs2rel module

Convert absolute music to relative music.

ly.pitch.abs2rel.abs2rel(cursor, language=u'nederlands', startpitch=True, first_pitch_absolute=False)[source]

Converts pitches from absolute to relative.

language: language to start reading pitch names in

startpitch: if True, write a starting pitch before the opening bracket of
a relative expression.
first_pitch_absolute: this option only makes sense when startpitch is False.

If first_pitch_absolute is True, the first pitch of a relative expression is written as absolute. This mimics the behaviour of LilyPond >= 2.18. (In fact, the starting pitch is then assumed to be f.)

If False, the first pitch is written as relative to c’ (LilyPond < 2.18 behaviour).

Existing relative expressions are not changed.

ly.pitch.rel2abs module

Convert relative music to absolute music.

ly.pitch.rel2abs.rel2abs(cursor, language=u'nederlands', first_pitch_absolute=False)[source]

Converts pitches from relative to absolute.

language: language to start reading pitch names in

first_pitch_absolute: if True, the first pitch of a relative expression

is regarded as absolute, when no starting pitch was given. This mimics the behaviour of LilyPond >= 2.18. (In fact, the starting pitch is then assumed to be f.)

If False, the starting pitch, when not given, is assumed to be c’ (LilyPond < 2.18 behaviour).

ly.pitch.translate module

Translating the language of pitch names

ly.pitch.translate.insert_language(document, language, version=None)[source]

Inserts a language command in the document.

The command is inserted at the top or just below the version line.

If the LilyPond version specified < (2, 13, 38), the include command is used, otherwise the newer language command.

ly.pitch.translate.translate(cursor, language, default_language=u'nederlands')[source]

Changes the language of the pitch names.

May raise ly.pitch.PitchNameNotAvailable if the current pitch language has no quarter tones.

Returns True if there also was a language or include language command that was changed. If not and the cursor specified only a part of the document, you could warn the user that a language or include command should be added to the document. Or you could call insert_language to add a language command to the top of the document.

ly.pitch.transpose module

Transposing music.

class ly.pitch.transpose.ModalTransposer(numSteps=1, scaleIndex=0)[source]

Bases: object

Transpose pitches by number of steps within a given scale.

Instantiate with the number of steps (+/-) in the scale to transpose by, and a mode index. The mode index is the index of the major scale in the circle of fifths (C Major = 0).

static getKeyIndex(text)[source]

Get the index of the key in the circle of fifths.

‘Cb’ returns 0, ‘C’ returns 7, ‘B#’ returns 14.

transpose(pitch)[source]
class ly.pitch.transpose.ModeShifter(key, scale)[source]

Bases: ly.pitch.transpose.Transposer

Shift pitches to optional mode/scale.

The scale should be formatted in analogy to the scale in the Transposer parent class.

The key should be an instance of ly.pitch.Pitch.

closestPitch(pitch)[source]

Get closest pitch from scale.

If only one scale note with the same base step exist that is returned. Otherwise the closest is calculated.

transpose(pitch)[source]

Shift to closest scale pitch if not already in scale.

class ly.pitch.transpose.Simplifier(scale=None)[source]

Bases: ly.pitch.transpose.Transposer

Make complicated accidentals simpler by substituting naturals where possible.

transpose(pitch)[source]
class ly.pitch.transpose.Transposer(fromPitch, toPitch, scale=None)[source]

Bases: object

Transpose pitches.

Instantiate with a from- and to-Pitch, and optionally a scale. The scale is a list with the pitch height of the unaltered step (0 .. 6). The default scale is the normal scale: C, D, E, F, G, A, B.

scale = (0, 1, 2, Fraction(5, 2), Fraction(7, 2), Fraction(9, 2), Fraction(11, 2))
transpose(pitch)[source]
ly.pitch.transpose.transpose(cursor, transposer, language=u'nederlands', relative_first_pitch_absolute=False)[source]

Transpose pitches using the specified transposer.

If relative_first_pitch_absolute is True, the first pitch in a relative expression is considered to be absolute, when a startpitch is not given. This is LilyPond >= 2.18 behaviour.

If relative_first_pitch_absolute is False, the first pitch in a relative expression is considered to be relative to c’, is no startpitch is given. This is LilyPond < 2.18 behaviour.

Currently, relative_first_pitch_absolute defaults to False.