Tutorial 2 - NoteContainers

What if we want to store several Note objects at once (ie. intervals, chords)? We could use a simple list and be done with it, but we could also use a NoteContainer, which has some extra functionality and is used throughout this package.

>>> from mingus.containers import NoteContainer

Creating a New NoteContainer

A new NoteContainer is easily created. You can create empty ones or ones already filled with notes:

>>> n = NoteContainer()
>>> n
[]
>>> n = NoteContainer(Note("A", 4))
>>> n
['A-4']
>>> n = NoteContainer("A")
>>> n
['A-4']
>>> n = NoteContainer(["A-3", "C-5", "E-5"])
>>> n
['A-3', 'C-5', 'E-5']

Adding Notes to a NoteContainer

Add a single note as a string (“C”, “C-5”, etc.) or a Note object.

>>> n = NoteContainer()
>>> n.add_note("C")
>>> n
['C-4']

Add multiple notes as a list of Note object or strings; or as another NoteContainer. Single notes still work as well. The following examples all produce the same NoteContainer:

>>> n = NoteContainer()
>>> n.add_notes(["C", "E"])

>>> n.empty()
>>> n.add_notes(NoteContainer(["C", "E"])

>>> n.empty()
>>> n.add_notes([Note("C"), Note("E")])

>>> n.empty()
>>> n.add_notes(Note("C"))
>>> n.add_notes(Note("E"))

Removing Notes from a NoteContainer

Remove a single note:

>>> n = NoteContainer(["C", "E", "G"])
>>> n.remove_note("E")
['C-4', 'G-4']
>>> n = NoteContainer(["C-4", "C-5"])
>>> n.remove_note("C")
[]

Removing a single note in a single octave:

>>> n = NoteContainer(["C-4", "C-5"])
>>> n.remove_note("C", 4)
['C-5']

Removing Multiple Notes from a NoteContainer

Removing more than one note from a NoteContainer:

>>> n = NoteContainer(["C", "E", "G"])
>>> n.remove_notes(["C", "E"])
['G-4']

The function remove_notes accepts lists of strings and Note objects, but does also accepts all the things remove_note accepts.

Using NoteContainers as Lists

Some basic operators and functions are overloaded which will allow you to work on NoteContainers as if they were lists.

>>> n = NoteContainer(["C", "E", "G"])
>>> n[0]
'C-4'
>>> n[:-1]
['C-4', 'E-4']
>>> n[0] = "D"
>>> n
['D-4', 'E-4', 'G-4']
>>> len(n)
3

The Overloaded ‘+’ Operator

The ‘+’ operator is overloaded for NoteContainer objects. This means that you can use ‘+’ instead of the verbose add_notes() function.

>>> n = NoteContainer()
>>> n + "C"
['C-4']
>>> n + ["E", "G"]
["C-4", "E-4", "G-4"]

The Overloaded ‘-‘ Operator

The ‘-‘ operator is overloaded as well and redirects calls to remove_notes. It can be used like this:

>>> n = NoteContainer(["C", "E", "G"])
>>> n - "E"
['C-4', 'G-4']
>>> n - ["C", "G"]
[]

Other methods

The methods available in Note -transpose, augment, diminish, to_major and to_minor- are also available for NoteContainers. When one of these functions get called the NoteContainer calls the functions on every one of his Note objects.

An extra function is available to determine the type of chord or interval in the container.

>>> n = NoteContainer(["C", "E", "G"])
>>> n.determine()
['C major triad']
>>> n.determine(True)
['Cmaj']

You can learn more about mingus.containers.NoteContainers in the reference section.