Extending music21 with Additional Software

Installing Additional Python Modules

Music21 can do more things, such as plotting graphs, if you install additional Python libraries.

The following topics cover additional software used by music21. For each library, visit the websites listed below, download the additional python libraries, and install them just as you did with music21 above. If you don’t feel like installing them now, no worries: you can always install them later.

It’s best not to install these until you have music21 working without the external modules.

Note: as of music21 v.6, some of these additional modules are bundled with music21


Graphing and visual displays in Music21 are provided by Matplotlib. Matplotlib itself has additional dependencies (such as NumPy).

On Mac if you are using the version from python.org, run:

pip3 install matplotlib

and you should be set. If you are using a version from anaconda (conda, miniconda, etc.), you should run these lines:

conda install matplotlib conda install python.app


Numeric extensions to Python. Included with Matplotlib.

On Mac if you are using the version of python 3 from python.org, run:

pip3 install numpy

and you should be set.


Scientific extensions to Python. These are used to accelerate audio searching and fast-Fourier transforms in music21. If you will only be using symbolic music, it is not used, and not essential in any case.

On Mac if you are using the version from python.org, run:

pip3 install scipy

and you should be set.


Allows for recording within python. We use it for the audioSearch module, and nowhere else. Not essential. Requires portaudio and, on the Mac, the XCode command-line development tools.

On the Mac, run:

xcode-select –install brew install portaudio pip3 install pyaudio


Allows for realtime MIDI performance. We use it in the midi.realtime module, and nowhere else. It is therefore not essential.

On the Mac, run:

pip3 install pygame

Installing Additional Software Components

Additional functionality of music21 is available with the installation of numerous helper applications. While not essential for all applications, these tools will aid in working with music21.


MuseScore offers a free, full-featured, cross-platform (Windows, Mac OS, Ubuntu, Debian, and Fedora) application for viewing and editing music notation. MuseScore can import and export MusicXML, and provides an excellent way to view, edit, and export musical data for working in music21. Downloading MuseScore (version 2 or higher) is highly recommended for working with music21.



Lilypond is a free, open-source music display program that can produce beautiful scores. Music21 can generate PDF or PNG (like JPG) files automatically if Lilypond is installed on your system. Download it at: