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matlab.engine.MatlabEngine class

Package: matlab.engine

Python object using MATLAB as computational engine within Python session

Description

The MatlabEngine class uses a MATLAB® process as a computational engine for Python®. You can call MATLAB functions as methods of a MatlabEngine object because the functions are dynamically invoked when you call them. You also can call functions and scripts that you define. You can send data to, and retrieve data from, the MATLAB workspace associated with a MatlabEngine object.

Construction

The matlab.engine.start_matlab function creates a MatlabEngine object each time it is called. There is no need to call matlab.engine.MatlabEngine() to create MatlabEngine objects of your own.

Methods

You can call any MATLAB function as a method of a MatlabEngine object. The engine dynamically invokes a MATLAB function when you call it. The syntax shows positional, keyword, and output arguments of a function call.

ret = MatlabEngine.matlabfunc(*args,nargout=1,async=False,stdout=sys.stsdout,stderr=sys.stderr)

Replace matlabfunc with the name of any MATLAB function (such as isprime or sqrt). Replace *args with input arguments for the MATLAB function you call. The keyword arguments specify:

  • The number of output arguments the function returns

  • Whether the engine calls the function asynchronously

  • Where the engine sends standard output and standard error coming from the function

Specify keyword arguments only when specifying values that are not the default values shown in the syntax.

Input Arguments to MATLAB Function

ArgumentDescriptionPython Type

*args

Input arguments to MATLAB function, specified as positional arguments

Any Python types that the engine can convert to MATLAB types

Keyword Arguments to Engine

ArgumentDescriptionPython Type

nargout

Number of output arguments from MATLAB function

int

Default: 1

async

Flag to call MATLAB function asynchronously

bool

Default: False

stdout

Standard output

StringIO.StringIO object (Python 2.7)
io.StringIO object (Python 3.x)

Default: sys.stdout

stderr

Standard error

StringIO.StringIO object (Python 2.7)
io.StringIO object (Python 3.x)

Default: sys.stderr

Output Arguments

Output TypeDescriptionRequired Keyword Arguments

Python variable

One output argument from MATLAB function

Default values

tuple

Multiple output arguments from MATLAB function

nargout=n (where n > 1)

None

No output argument from MATLAB function

nargout=0

FutureResult object

A placeholder for output arguments from asynchronous call to MATLAB function

async=True

Exceptions

MatlabExecutionError

Function call fails to execute

RejectedExecutionError

MATLAB engine terminated

SyntaxError

Syntax error in a function call

TypeError

Data type of an input or output argument not supported

Attributes

workspace

Python dictionary containing references to MATLAB variables. You can assign data to, and get data from, a MATLAB variable through the workspace. The name of each MATLAB variable you create becomes a key in the workspace dictionary. The keys in workspace must be valid MATLAB identifiers (for example, you cannot use numbers as keys).

Examples

expand all

Call the MATLAB sqrt function from Python using the engine.

import matlab.engine
eng = matlab.engine.start_matlab()
ret = eng.sqrt(4.0)
print(ret)
2.0

Create an array in Python and put it into the MATLAB workspace.

import matlab.engine
eng = matlab.engine.start_matlab()
px = eng.linspace(0.0,6.28,1000)

px is a MATLAB array, but eng.linspace returned it to Python. To use it in MATLAB, put the array into the MATLAB workspace.

eng.workspace['mx'] = px

When you add an entry to the engine workspace dictionary, you create a MATLAB variable, as well. The engine converts the data to a MATLAB data type.

Get pi from the MATLAB workspace and copy it to a Python variable.

import matlab.engine
eng = matlab.engine.start_matlab()
eng.eval('a = pi;',nargout=0)
mpi = eng.workspace['a']
print(mpi)
3.14159265359

Introduced in R2014b

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