tabr (version 0.4.0)

scale-deg: Scale degrees and mappings

Description

These functions assist with mapping between scale degrees, notes and chords.

Usage

scale_degree(
  notes,
  key = "c",
  scale = "diatonic",
  use_root = TRUE,
  strict_accidentals = TRUE,
  naturalize = FALSE,
  roman = FALSE
)
scale_note(deg, key = "c", scale = "diatonic", collapse = FALSE, ...)
note_in_scale(
  notes,
  key = "c",
  scale = "diatonic",
  use_root = TRUE,
  strict_accidentals = TRUE
)
chord_degree(
  notes,
  key = "c",
  scale = "diatonic",
  strict_accidentals = TRUE,
  naturalize = FALSE,
  roman = FALSE
)
is_in_scale(notes, key = "c", scale = "diatonic", strict_accidentals = TRUE)

Arguments

notes

character, a string of notes.

key

character, key signature (or root note) for scale, depending on the type of scale.

scale

character, the suffix of a supported scale_* function.

use_root

logical, use lowest pitch in chord. Otherwise yield an NA in output.

strict_accidentals

logical, whether representation must match key and scale. See details.

naturalize

logical, whether to naturalize any sharps or flats before obtaiuning the scale degree.

roman

logical, return integer scale degrees as Roman numerals.

deg

integer, roman class, or character roman, the scale degree.

collapse

logical, collapse result into a single string ready for phrase construction.

...

additional arguments passed to the scale function, e.g., sharp = FALSE for scale_chromatic.

Value

integer, or roman class if roman = TRUE for scale_degree. character for scale_note.

Details

Obtain the scale degree of a note in a supported scale with scale_degree. This function works on any noteworthy string. It ignores octave numbering. Rests and any note not explicitly in the scale return NA. If deg is greater than the number of degrees in the scale, it is recycled, e.g., in C major 8 starts over as C.

By default, flats and sharps checked strictly against the scale. Setting strict_accidentals = FALSE will convert any flats or sharps present, if necessary based on the combination of key signature and scale. The chromatic scale is a special case where strict accidental is always ignored.

Not any arbitrary combination of valid key and valid scale is valid. For example, key = "am" and scale = "harmonic" is valid, but not with key = "a".

note_in_scale is a wrapper around scale_degree. To check if full chords are diatonic to the scale, see is_diatonic.

The inverse of scale_degree is scale_note, for obtaining the note associated with a scale degree. This could be done simply by calling a scale_* function and indexing its output directly, but this wrapper is provided to complement scale_degree. Additionally, it accepts the common Roman numeral input for the degree. This can be with the roman class or as a character string. Degrees return NA if outside the scale degree range.

See Also

scale-helpers, is_diatonic

Examples

# NOT RUN {
scale_degree("r c, e3 g~ g s g# ceg")
note_in_scale("r c, e3 g~ g s g# ceg")

scale_degree("c e g", roman = TRUE)

scale_degree("c c# d_ e", key = "d")
scale_degree("c c# d_ e", key = "d", strict_accidentals = FALSE)

scale_degree("c, e_3 g' f#ac#", use_root = FALSE)
scale_degree("c, e_3 g' f#ac#", naturalize = TRUE) # lowest chord pitch: c#

scale_degree("c# d_ e_' e4 f f# g", key = "c#", scale = "chromatic")

scale_note(1:3, key = "am")
scale_note(c(1, 3, 8), "d", collapse = TRUE)
all(sapply(list(4, "IV", as.roman(4)), scale_note) == "f")

x <- "d dfa df#a f#ac#"
chord_degree(x, "d")
is_in_scale(x, "d")
# }