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Introduction

Chord Progressions is a Python library of utility functions for working with chord progressions.

Installation

$ pip install chord-progressions

Usage

The simplest way to create a Progression is with a list of chords specified in MIDI note numbers.

from chord_progressions import Progression

progression = Progression(chords=[[69, 84, 90, 99], [60, 67, 71, 87, 98]])

[
    {
        "id": "ea1b9a6a-e309-4e6a-bad8-04643e652015",
        "ix": 0,
        "duration": "1m",
        "type": "diminished-seventh chord",
        "typeId": 139,
        "notes": [
            "A4",
            "C6",
            "F#6",
            "D#7"
        ],
        "midi_nums": [
            69,
            84,
            90,
            99
        ],
        "metrics": {
            "num_notes": 4,
            "num_pitches": 4,
            "pc_cardinality": 4,
            "interval_class_vector": [
                0,
                0,
                4,
                0,
                0,
                2
            ],
            "ambitus": 30,
            "evenness": 9.65685424949238
        }
    },
    {
        "id": "f36d4b52-9f8f-4b72-8693-34b60f23a564",
        "ix": 1,
        "duration": "1m",
        "type": "minor-major ninth chord",
        "typeId": 101,
        "notes": [
            "C4",
            "G4",
            "B4",
            "D#6",
            "D7"
        ],
        "midi_nums": [
            60,
            67,
            71,
            87,
            98
        ],
        "metrics": {
            "num_notes": 5,
            "num_pitches": 5,
            "pc_cardinality": 5,
            "interval_class_vector": [
                2,
                1,
                2,
                3,
                2,
                0
            ],
            "ambitus": 38,
            "evenness": 13.923559033019178
        }
    }
]

Each Chord in a Progression has the following attributes:

  • id: a UUID
  • ix: the index of the chord in the progression
  • type: the name of the chord, given by this list
  • typeId: a unique ID of the chord type
  • duration: specified in Tone.Time.Notation as one of ["8n", "4n", "4n.", "2n", "2n.", "1m", "2m"]
  • notes: the MIDI note names of the notes in the chord
  • metrics: a dictionary of attributes computed based on the notes in the chord