to_tabr: Music notation syntax converters

In tabr: Music Notation Syntax, Manipulation, Analysis and Transcription in R

Music notation syntax converters

Description

Convert alternative representations of music notation to tabr syntax.

Usage

to_tabr(id, ...)

from_chorrrds(x, key = "c", guitar = FALSE, gc_args = list())

from_music21(x, accidentals = c("flat", "sharp"), output = c("music", "list"))

Arguments

id	character, suffix of ⁠from_*⁠ function, e.g., "chorrrds"
...	arguments passed to the function matched by id.
x	character, general syntax input. See details and examples for how inputs are structured for each converter.
key	key signature, used to enforce consistent use of flats or sharps.
guitar	logical, attempt to match input chords to known guitar chords in guitarChords(). Otherwise by default standard piano chords of consecutive pitches covering minimum pitch range are returned.
gc_args	named list of additional arguments passed to gc_info(), used when guitar = TRUE.
accidentals	character, represent accidentals, "flat" or "sharp".
output	character, type of output when multiple options are available.

Details

These functions convert music notation from other data sources into the style used by tabr for music analysis and sheet music transcription.

Value

noteworthy string for chorrrds; music string or list for music21.

Syntax converter for chorrrds

The input x is a character vector of chords output from the chorrrds package, as shown in the examples. Output is a noteworthy string object.

Some sources do not offer as complete or explicit information in order to make sheet music. However, what is available in those formats is converted to the extent possible and available function arguments can allow the user to add some additional specification. Different input syntax makes use of a different syntax converter. Depending on the format, different arguments may be available and/or required. The general wrapper function for all of the available syntax converters is to_tabr(). This function takes an id argument for the appropriate converter function. See examples.

For example, output from the chorrrds package that scrapes chord information from the Cifraclub website only provides chords, not note for note transcription data for any particular instrument. This means the result of syntax conversion still yields only chords, which is fine for data analysis but doesn't add anything useful for sheet music transcription.

The input in this case also does not specify distinct pitches by assigning octaves numbers to a chord's notes, not even the root note. It remains up to the user if they want to apply the information. By default, every chord starts in octave three. It is also ambiguous how the chord is played since all that is provided is a generic chord symbol. By default a standard chord is constructed if it can be determined.

Setting guitar = TRUE switches to using the guitarChords() dataset to find matching guitar chords using gc_info(), which can be provided additional arguments in a named list to gc_args. For guitar, this allows some additional control over the actual structure of the chord, its shape and position on the guitar neck. The options will never work perfectly for all chords in chords, but at a minimum, typical default component pitches will be determined and returned in tabr notation style.

Syntax converter for music21

The input x is a character vector of in music21 tiny notation syntax, as shown in the examples. Default output is a music object. Setting output = "list" returns a list of three elements: a noteworthy string, a note info string, and the time signature.

The recommendation for music21 syntax is to keep it simple. Do not use the letter n for explicit natural notes. Do not add text annotations such as lyrics. Double flats and sharps are not supported. The examples demonstrate what is currently supported.

Examples

# chorrrds package output
chords <- c("Bb", "Bbm", "Bbm7", "Bbm7(b5)", "Bb7(#5)/G", "Bb7(#5)/Ab")
from_chorrrds(chords)
to_tabr(id = "chorrrds", x = chords)

from_chorrrds(chords, guitar = TRUE)
to_tabr(id = "chorrrds", x = chords, guitar = TRUE)

# music21 tiny notation
x <- "4/4 CC#FF4.. trip{c#8eg# d'- e-' f g a'} D4~# D E F r B16"
from_music21(x)

from_music21(x, accidentals = "sharp")

from_music21(x, output = "list")

tabr documentation built on Sept. 21, 2023, 5:06 p.m.