Call Python function from MATLAB

Question

I need to call a Python function from MATLAB  how can I do this

User · Answer

Since MATLAB seamlessly integrates with Java  you can use Jython to write your script and call that from MATLAB  you may have to add a thin pure JKava wrapper to actually call the Jython code   I never tried it  but I can t see why it won t work

User · Answer

I had a similar requirement on my system and this was my solution    In MATLAB there is a function called perl m  which allows you to call perl scripts from MATLAB  Depending on which version you are using it will be located somewhere like  C  Program Files MATLAB R2008a toolbox matlab general perl m   Create a copy called python m  a quick search and replace of perl with python  double check the command path it sets up to point to your installation of python  You should now be able to run python scripts from MATLAB   Example  A simple squared function in python saved as  sqd py   naturally if I was doing this properly I d have a few checks in testing input arguments  valid numbers etc   import sys  def squared x       y   x   x     return y  if   name         main         x   float sys argv 1       sys stdout write str squared x      Then in MATLAB   gt  gt  r python  sqd py   3 5   r   12 25  gt  gt  r python  sqd py   5   r   25 0  gt  gt

User · Answer

Like Daniel said you can run python commands directly from Matlab using the py  command   To run any of the libraries you just have to make sure Malab is running the python environment where you installed the libraries   On a Mac    Open a new terminal window  type  which python  to find out where the default version of python is installed   Restart Matlab  type  pyversion   anaconda2 bin python    in the command line  obviously replace with your path   You can now run all the libraries in your default python installation     For example           py sys version           py sklearn cluster dbscan

User · Answer

Try this MEX file for ACTUALLY calling Python from MATLAB not the other way around as others suggest  It provides fairly decent integration   http   algoholic eu matpy   You can do something like this easily    X Y  meshgrid -10 0 1 10 -10 0 1 10   Z sin X  cos Y   py export  X   Y   Z   stmt   sprintf   import matplotlib n       matplotlib use   Qt4Agg    n       import matplotlib pyplot as plt n       from mpl toolkits mplot3d import axes3d n       f plt figure   n       ax f gca projection   3d    n       cset ax plot surface X Y Z  n       ax clabel cset fontsize 9 inline 1  n       plt show       py  eval   stmt

User · Answer

This seems to be a suitable method to  tunnel  functions from Python to MATLAB   http   code google com p python-matlab-wormholes   The big advantage is that you can handle ndarrays with it  which is not possible by the standard output of programs  as suggested before   Please correct me  if you think this is wrong - it would save me a lot of trouble  -

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I ve adapted the perl m to python m and attached this for reference for others  but I can t seem to get any output from the Python scripts to be returned to the MATLAB variable     Here is my M-file  note I point directly to the Python folder  C  python27 64  in my code  and this would change on your system   function  result status    python varargin  cmdString       for i   1 nargin     thisArg   varargin i       if isempty thisArg      ischar thisArg          error  MATLAB python InputsMustBeStrings    All input arguments must be valid strings         end     if i  1         if exist thisArg   file    2             if isempty dir thisArg                   thisArg   which thisArg               end         else             error  MATLAB python FileNotFound    Unable to find Python file   s   thisArg           end     end   if any thisArg             thisArg         thisArg          end   cmdString    cmdString       thisArg   end errTxtNoPython    Unable to find Python executable    if isempty cmdString    error  MATLAB python NoPythonCommand    No python command specified    elseif ispc   pythonCmd    C  python27 64     cmdString     python  cmdString       pythonCmd     set PATH   pythonCmd     PATH  amp   cmdString      status  result    dos pythonCmd  else    status ignore    unix  which python      ok   if  status    0      cmdString     python   cmdString        status  result    unix cmdString     else     error  MATLAB python NoExecutable   errTxtNoPython     end end if nargout  lt  2  amp  amp  status  0   error  MATLAB python ExecutionError                System error   sCommand executed   s   result  cmdString   end   EDIT    Worked out my problem the original perl m points to a Perl installation in the MATLAB folder by updating PATH then calling Perl  The function above points to my Python install  When I called my function py file  it was in a different directory and called other files in that directory  These where not reflected in the PATH  and I had to easy install my Python files into my Python distribution

User · Answer

The simplest way to do this is to use MATLAB s system function    So basically  you would execute a Python function on MATLAB as you would do on the command prompt  Windows   or shell  Linux    system  python pythonfile py     The above is for simply running a Python file  If you wanted to run a Python function  and give it some arguments   then you would need something like   system  python pythonfile py argument     For a concrete example  take the Python code in Adrian s answer to this question  and save it to a Python file  that is test py  Then place this file in your MATLAB directory and run the following command on MATLAB   system  python test py 2     And you will get as your output 4 or 2 2   Note  MATLAB looks in the current MATLAB directory for whatever Python file you specify with the system command   This is probably the simplest way to solve your problem  as you simply use an existing function in MATLAB to do your bidding

User · Answer

Starting from Matlab 2014b Python functions can be called directly  Use prefix py  then module name  and finally function name like so   result   py module name function name parameter1     Make sure to add the script to the Python search path when calling from Matlab if you are in a different working directory than that of the Python script   See more details here

User · Answer

You could embed your Python script in a C program and then MEX the C program with MATLAB but that might be a lot of work compared dumping the results to a file   You can call MATLAB functions in Python using PyMat  Apart from that  SciPy has several MATLAB duplicate functions   But if you need to run Python scripts from MATLAB  you can try running system commands to run the script and store the results in a file and read it later in MATLAB

User · Answer

A little known  and little documented  fact about MATLAB s system   function   On unixoid systems it uses whatever interpreter is given in the environment variable SHELL or MATLAB SHELL at the time of starting MATLAB  So if you start MATLAB with  SHELL   usr bin python  matlab   any subsequent system   calls will use Python instead of your default shell as an interpreter

User · Answer

Since Python is a better glue language  it may be easier to call the MATLAB part of your program from Python instead of vice-versa     Check out Mlabwrap

User · Answer

With Matlab 2014b python libraries can be called directly from matlab  A prefix py  is added to all packet names    gt  gt  wrapped   py textwrap wrap  example    wrapped       Python list with no properties         example

User · Answer

As  dgorissen said  Jython is the easiest solution   Just install Jython from the homepage   Then   javaaddpath   path-to-your-jython-installation jython jar    import org python util PythonInterpreter   python   PythonInterpreter     takes a long time to load  python exec  import some module    python exec  result   some module run something      result   python get  result      See the documentation for some examples   Beware  I never actually worked with Jython and it seems that the standard library one may know from CPython is not fully implemented in Jython   Small examples I tested worked just fine  but you may find that you have to prepend your Python code directory to sys path

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