pyversion: "Path argument does not specify a valid executable."

Hi,

I have 32-bit version of MATLAB 2014b (8.4.0.150421 (R2014b)) and a 32 bit version of python (Python 2.7.9 (default, Dec 10 2014, 12:24:55) [MSC v.1500 32 bit (Intel)] on win32) on a windows 7 64-bit machine. I installed python using the standard installer on python.org. I have python in the system path (which MATLAB confirms when I use a "getenv('PATH')" command.) Every time I try to get pyversion to recognize python, I get "Error using pyversion: Path argument does not specify a valid executable." I have tired using just 2.7 as an argument as well as the full path to the executable 'C:\Python27\python.exe'. (And I've confirmed python really is there.) Is there something I'm missing, or haven't set up properly?

Thanks!

[Robert Snoeberger]

I tried 32-bit Python with 32-bit MATLAB on 64-bit Windows and it worked for me. Did you check that Python is working properly? You could try running a few commands from MATLAB with bang.

>> !C:\Python27_32\pythonw.exe -V
Python 2.7.9 
>> !C:\Python27_32\pythonw.exe -c "import sys; print sys.executable, sys.prefix"
C:\Python27_32\pythonw.exe C:\Python27_32
>>

Another issue could be the location of python27.dll. If you installed Python for only the current user, it is located in the same folder as the executable.

[Joe Sheridan]

Thank you very much for trying this on your computer. When I do

!C:\Python27\python.exe -V

I get the version. When I do

!C:\Python27\pythonw.exe -V

I get no output, but it does return w/o any error. The command you had passing code works just like you have with python.exe.

Thank you for your reply and help with this!

[Joe Sheridan]

One other thing that's really strange. I can call MATLAB from python, and when I do pyversion gives the correct value.

>>> eng = matlab.engine.start_matlab();
>>> eng.pyversion();
'2.7'

[Robert Snoeberger]

What about pyversion with nargout=0?

>>> eng.pyversion(nargout=0)

[Dmitry]

Python environment settings are stored in matlab.settings file in the prefdir (MATLAB preferences directory) of user which is MATLAB is started by. They are in section:

    <settings name="external">
        <settings name="interfaces">
            <settings name="python">
                <key name="Version">

Under my Win 8.1 environment, for example, they look like this:

                    <string minArraySize="4" maxArraySize="4">
                        <value><![CDATA[3.4]]></value>
                        <value><![CDATA[C:\Anaconda3\python.exe]]></value>
                        <value><![CDATA[C:\Anaconda3]]></value>
                        <value><![CDATA[C:\Anaconda3\python34.dll]]></value>
                    </string>

Under Ubuntu environment it looks like this:

<string minArraySize="4" maxArraySize="4">
                        <value><![CDATA[3.4]]></value>
                        <value><![CDATA[/root/anaconda3/bin/python]]></value>
                        <value><![CDATA[/root/anaconda3]]></value>
                        <value><![CDATA[/root/anaconda3/lib/libpython3.4m.so]]></value>
                    </string>

When I've got an error Joe Sheridan have mentioned, I just inserted applicable paths into matlab.settings directly.

Also, at least under Ubuntu it is hard to predict, which matlab.settings file MATLAB will use - I've ran into cases when MATLAB was started under one user and was using matlab.settings of another user.