Reading and writing mmt files

This page is about reading and writing the mmt format used by Myokit. For information about using Myokit with other formats, please check out the API :: Formats section.

Myokit models can be loaded form disk using load() and stored using save(). Both these functions assume you’re working with a full (model, protocol, script) tuple. Support for partial loading and saving is provided through functions like load_model() and split().

Basic commands


Reads an mmt file and returns a tuple (model, protocol, embedded script).

If the file specified by filename doesn’t contain one of these parts the corresponding entry in the tuple will be None., model=None, protocol=None, script=None)

Saves a model, protocol, and embedded script to an mmt file.

The model argument can be given as plain text or a myokit.Model object. Similarly, protocol can be either a myokit.Protocol or its textual represenation.

If no filename is given the mmt code is returned as a string.


Parses strings in mmt format and returns a tuple (model, protocol, embedded script).

None may be returned for any segment not appearing in the source.

The source to parse can be given as a plain string, a sequence of lines or a stream of lines.

Using parts of mmt files


Loads the model section from an mmt file.

Raises a SectionNotFoundError if no model section is found.


Loads the protocol section from an mmt file.

Raises a SectionNotFoundError if no protocol section is found.


Loads the script section from an mmt file.

Raises a SectionNotFoundError if no script section is found.


Attempts to split the source into model, protocol and script segments. Any content before the [[model]] tag is discarded.

myokit.save_model(filename, model)

Saves a model to a file

myokit.save_protocol(filename, protocol)

Saves a protocol to a file

myokit.save_script(filename, script)

Saves an embedded script to a file

Parsing parts mmt files


Parses a model in mmt format.


Parses a protocol in mmt format.

Parsing expressions

myokit.parse_expression(string, context=None)

Parses string data into a myokit.Expression.

A myokit.Variable object can be given as context to resolve any references against.


Parses string data into a myokit.Number.

Parsing units


Parses string data into a myokit.Unit.

Parse errors

Errors with the underlying file system (file not found, file corrupt etc) will result in ordinary Python IO errors. Any other errors occurring during parsing should be of the type ParseError.

myokit.format_parse_error(ex, source=None)

Turns a ParseError ex into a detailed error message.

If a filename or input stream is passed in as source, this will be used to show the line on which an error occurred. If a stream is passed, it should be rewinded to the same point the original parsing started.

A note about the format

The mmt format consists of several sections (each with their own syntax) stored sequentially in a single, string-based format. In theory, this means mmt files containing syntax errors cannot be reliably separated into parts. For example if a string isn’t terminated in one section, it is impossible to tell if a subsequent section header indicates a new section or is part of the string.

These problems could be avoided in a more complicated format, for example a zip file containing separate files for each section. However, using a plain-text format makes mmt files human readable, loadable in any text editor and directly suitable for storage in versioning systems.