coltrane

Coltrane

A music calculation library/CLI written in Ruby.

CLI (Command Line Interface)

Features

• Generate chord progressions for Jazz, Blues, Pop, or custom and see how to play them
• Seek chords, see their notes and how to play them
• Seek scales, see their notes and see how to play them
• Find chords that are common between 2 scales
• Find scales containing a chord or a set of notes
• Find possible progressions of a chord sequence
• All of the above can be seen on guitar, bass, piano or ukelele representations, no sheet music needed

How to discover a chord name using the notes

coltrane find chord by notes notes:C-E-G

CM:  C E G

To see it on guitar:

…

PS: It looks way better on the terminal , specially on iTerm

How to discover a Scale by providing chords

You shall provide chords separated by dashes (--chords CM7-Dm7-EM) or notes (--notes C-Ab-F-G).

For example:

…

When on terminal, the command above will highlight the Scales that have all needed notes. The number in the parenthesis show how many chord notes were included.

How to find common chords

You may use this command to find a chord that may serve as bridge to a different scale/key (i.e. modulation). Coltrane offers you a command to find common chords shared between both keys/scales. Here is how you use it. Say you wanna transition from C Major to D Natural Minor.

coltrane find common chords in scales

Dm:  D F A
Am:  A C E
Dm7: D F A C
Am7: A C E G
CM:  C E G
FM:  F A C
CM6: C E G A
FM6: F A C D
C6/9: C E G A D
F6/9: F A C D G
C6/9(add11): C E G A D F
[...]

You can also see the output in a graphical representation:

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Quickly generate chord progressions

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You can say Jazz, Pop, Blues, etc. You can also generate progressions in a custom way, using roman numerals:

coltrane custom progression progression_notation:I-vi-V-iidim representation:Text key:D

Generate fretboard sheets for improvising

Sometimes you wanna see the scale on guitar for improvising:

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ProTip: You can force the guitar frets visualization for chords too using the --on guitar_frets option.

Finding the progression of a chord sequence

Perhaps this is the most complex operation that Coltrane performs. It searches the chords on all known scales, generates the progression notation and print in, sorted by notes left out. That is because most songs, specially knowadays, may use chords that contain notes which are outside of that scale.

This command us to analyze songs and discover what they have in common, even tho they have different notes.

Let's say we want to find the possible progressions of Red Hot Chili Pepper's Otherside:

…

PS: Notice that vi-IV-I-V is the well known I-V-vi-IV progression, used in a lot of songs.

Interactive mode (shell)

Simply type coltrane or coltrane shell to enable interactive mode. You can then run commands without typing coltrane before, E.G.: scale D harmonic minor

Installation

Installation is done through the RubyGems package manager:

gem install coltrane

[!NOTE] RubyGems comes packaged with the standard Ruby installation. You can find instructions on how to install Ruby here.

Once you install the gem, the CLI is installed in your system and it's ready to be used.

Any questions? Feature requests? Bugs?

1. Find me on Twitter. I'll be glad to answer.
2. Open an issue.
3. Join our chatroom

Extra

• How to use the Core Theory library.
• Why did I write this library
• See the changelog

Contributing

How to contribute

1. Fork this code
2. Install the test suite (RSpec) by running good old bundle command
3. Make your changes and maybe write a test or two.
4. Check if specs pass bundle exec rspec spec
5. Submit a PR.

License

The gem is available as open source under the terms of the MIT License.

by Pedro Maciel | twitter | [email protected]