Struct RomanNumeral 

pub struct RomanNumeral { /* private fields */ }

A parsed Roman numeral in a key.

Implementations

impl RomanNumeral

pub fn analyze(chord: &Chord, key: Key) -> Result<Option<Self>>

Performs functional Roman-numeral analysis in a key.

pub fn analyze_with_root( chord: &Chord, key: Key, root: &Pitch, ) -> Result<Option<Self>>

Performs Roman-numeral analysis using an explicit harmonic root.

This is useful for pitch-class-set browser views where the caller has already chosen a transposition root and does not want inversion or root inference to pick a different chord member.

impl RomanNumeral

pub fn to_chord(&self) -> Result<Chord>

The chord the numeral stands for, spelled where its key sounds.

This is music21’s _updatePitches, and it is a figured-bass reading rather than a stack of intervals: the bass is the scale degree the inversion figure puts there, every number of the column is that many scale steps above it, and only then is the result respelled to the quality the numeral’s case and symbols asked for. Reading it off the scale is what lets a numeral mean something in a mode, and what makes V7b5 alter one note rather than name a different chord.

impl RomanNumeral

pub fn new(figure: impl Into<String>, key: Key) -> Result<Self>

Parses a Roman numeral figure in a key.

Supports ordinary figures such as V7/V and augmented-sixth figures such as It+6, Fr+6, Ger+6, and Sw+6.

pub fn with_minor_defaults( figure: impl Into<String>, key: Key, sixth_minor: Minor67Default, seventh_minor: Minor67Default, ) -> Result<Self>

The same, saying how the sixth and seventh degrees of a minor key are to be read: music21’s sixthMinor and seventhMinor.

pub fn with_options( figure: impl Into<String>, key: Key, sixth_minor: Minor67Default, seventh_minor: Minor67Default, case_matters: bool, ) -> Result<Self>

The same again, saying whether the case of the numeral states the chord’s quality: music21’s caseMatters.

pub fn over_scale( figure: impl Into<String>, key: Key, scale: Option<Scale>, sixth_minor: Minor67Default, seventh_minor: Minor67Default, case_matters: bool, ) -> Result<Self>

The same again over a scale that is not a key: music21’s numerals read against a ConcreteScale.

The key is still needed — a numeral reports one, and a secondary numeral establishes one — so pass the major key of the scale’s tonic, which is what music21 falls back on.

pub fn bracketed_alterations(&self) -> &[(i8, u8)]

The alterations written in square brackets, as the semitones each moves its chord step by and the step it moves.

pub fn omitted_steps(&self) -> &[u8]

The chord steps the figure leaves out, as [no3].

pub fn added_steps(&self) -> &[(i8, u8)]

The notes the figure puts in beside the chord, as [add4]: the alteration in semitones and how far above the root each stands.

pub fn scale(&self) -> Option<&Scale>

The scale the figure is read over, where it is not a key at all.

A numeral read this way spells its chord where the scale stands, so nothing downstream has to place it.

pub fn implied_quality(&self) -> ImpliedQuality

The quality the figure states, which is what the notes read off the scale are respelled to.

pub fn figure_numbers(&self) -> Vec<u8>

The numbers of the figured-bass column the figure’s digits stand for, written high to low and expanded out of music21’s shorthand.

pub fn case_matters(&self) -> bool

Whether the case of the numeral states the chord’s quality.

pub fn sixth_minor(&self) -> Minor67Default

How this numeral reads the sixth degree of a minor key.

pub fn seventh_minor(&self) -> Minor67Default

How it reads the seventh.

pub fn figures_written(&self) -> &str

Returns the original figure. The digits written under the numeral, as music21’s figuresWritten: the figure with the numeral, its accidental and its quality symbol taken off it, and nothing expanded.

pub fn figures_notation(&self) -> &Notation

The figured-bass column the numeral’s digits stand for, expanded out of the shorthand they were written in: music21’s figuresNotationObj.

pub fn figure(&self) -> &str

The figure the numeral was written with, as given: music21’s figure.

pub fn degree(&self) -> u8

Returns the one-based scale degree.

pub fn written_accidental(&self) -> i8

Returns the chromatic alteration of the scale degree in semitones.

Negative values are flats and positive values are sharps, so bII returns -1 and #iv returns 1.

pub fn accidental(&self) -> i8

The alteration the numeral reports, once the sixth and seventh degrees of a minor key have been read against the chord asked for.

pub fn inversion(&self) -> u8

Returns the inversion number, where root position is 0.

pub fn secondary(&self) -> Option<&str>

Returns the secondary/applied target figure, if any.

pub fn key(&self) -> &Key

Returns the key context.

pub fn roman_numeral(&self) -> String

The numeral with its front alteration and nothing else: music21’s romanNumeral, so bII6 is bII and V65/V is V. An augmented sixth answers its nationality, It, Fr, Ger or Sw.

pub fn roman_numeral_alone(&self) -> String

The numeral with nothing written in front of it: music21’s romanNumeralAlone, so bVII65/V is VII.

pub fn figure_and_key(&self) -> String

The figure and its key together: music21’s figureAndKey, bII6 in a minor.

pub fn scale_degree_with_alteration(&self) -> (u8, i8)

The scale degree with the alteration in front of it, as sharps (positive) or flats (negative): music21’s scaleDegreeWithAlteration.

pub fn functionality_score(&self) -> u8

How strongly the figure implies its function, from music21’s functionalityScores table: I is 100, V7 80, an unknown figure 0. A secondary figure multiplies the scores of its halves. An augmented sixth is looked up by music21’s spelling, It6 rather than the It+6 this crate writes.

pub fn is_neapolitan(&self, require_first_inversion: bool) -> bool

Whether this is a Neapolitan chord: a major triad on the flattened second degree, in first inversion unless require_first_inversion is off.

pub fn is_mixture(&self, evaluate_secondary: bool) -> Result<bool>

Whether the chord is borrowed from the parallel mode: music21’s isMixture, so iv and bVI in a major key are mixture and IV in a minor key is. With evaluate_secondary a secondary figure is judged by the numeral after the slash.

pub fn transpose(&self, interval: &Interval) -> Result<Self>

The same figure in the key transposed by interval.

pub fn effective_key_of(&self) -> Result<Key>

The key the figure is actually read in: the key it was given, or the one a secondary numeral establishes — the V of V/V in G major is read in D major.

Trait Implementations

impl Clone for RomanNumeral

fn clone(&self) -> RomanNumeral

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for RomanNumeral

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for RomanNumeral

Available on crate feature serde only.

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for RomanNumeral

fn fmt(&self, formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Serialize for RomanNumeral

Available on crate feature serde only.

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.