matlab.engine.MatlabEngine - Python object using MATLAB as computational engine within Python session - MATLAB (original) (raw)
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Namespace: 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.
Creation
The matlab.engine.start_matlab method creates aMatlabEngine object each time it is called. There is no need to callmatlab.engine.MatlabEngine() to create MatlabEngine objects of your own.
Attributes
| Attribute | Description |
|---|---|
| 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). |
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,background=False,stdout=sys.stdout,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
| Argument | Description | Python 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
| Argument | Description | Python Type |
|---|---|---|
| nargout | Number of output arguments from MATLAB function | int Default: 1 |
| background | Flag to call MATLAB function asynchronouslybackground is an alias for async. However, as of Python Version 3.7, async is a keyword and cannot be used as an argument. Use the background argument instead ofasync for all supported versions of Python. | bool Default: False |
| stdout | Standard output | io.StringIO object Default: sys.stdout |
| stderr | Standard error | io.StringIO object Default: sys.stderr |
Output Arguments
| Output Type | Description | Required 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 | background=True |
Exceptions
| Exception | Description |
|---|---|
| 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 |
Examples
Call the MATLABsqrt function from Python using the engine.
import matlab.engine
eng = matlab.engine.start_matlab()
ret = eng.sqrt(4.0)
print(ret)
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.
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)
Version History
Introduced in R2014b