[Python.NET] Could you tell me how to call python from c#?

Barrett, Joey Joey.Barrett at itg.com
Wed Jun 6 21:01:56 CEST 2007


Thank you for all the help.

Loading a module located at C:\test\testModule.py is causing the
following error: "Object reference not set to an instance of an object."

TestModule.py

def testMethod(self, options = {}):
	m = {}
	return m


The last line of this code throws the error:

// setting up PYTHONPATH
System.Environment.SetEnvironmentVariable("PYTHONPATH",@"C:\test;");
PythonEngine.Initialize();
PyObject module = PythonEngine.ImportModule("testModule");
PyObject returnObject = module.InvokeMethod("testMethod", new
PyTuple());



Is this the correct way to import a module or can a fully specified path
be used?  For example:

PythonEngine.ImportModule("C:\test\testModule.py");


PythonEngine.Initialize() initializes the interpreter --- what
interpreter is initialized?  If Python is on the PATH, is that the
interpreter initialized?


Thanks, I really appreciate any tips.

Joey J. Barrett
Investment Technology Group, Inc.

 

-----Original Message-----
From: pythondotnet-bounces at python.org
[mailto:pythondotnet-bounces at python.org] On Behalf Of Michael Eddington
Sent: Wednesday, June 06, 2007 11:09 AM
To: pythondotnet at python.org
Subject: Re: [Python.NET] Could you tell me how to call python from c#?

Yes, you can set the PYTHONHOME variable from .net prior to calling
the initialize.  Many of the python runtimes set registry keys or are
located in default locations.

mike

On 6/6/07, Barrett, Joey <Joey.Barrett at itg.com> wrote:
>
> Thank you for your response, this is helpful.
>
> The methods called usually return lists or dictionaries and sometimes
> other types too that need to be used within the C#.  In the example
you
> provided the return value from InvokeMethod(), is a string
"fromPython",
> but I noticed InvokeMethod() actually returns a PyObject.
>
> How can I look at that PyObject and extract the returned values?
>
> The classes I use import many modules from a number of locations on
disk
> that aren't known to the interpreter.
>
> Is there a way to add to the PYTHONPATH programmatically in C# using
the
> Python for .net library, or would it be required to write a wrapper
> python module that adds to the path first?  Maybe there is another way
> to handle this?
>
> Thank you again
>
> Joey J. Barrett
> Investment Technology Group, Inc.
>
> -----Original Message-----
> From: Karpenstein, Nissim (C-BASS)
> [mailto:Nissim.Karpenstein at C-BASS.COM]
> Sent: Wednesday, June 06, 2007 6:37 AM
> To: Barrett, Joey; pythondotnet at python.org
> Subject: RE: [Python.NET] Could you tell me how to call python from
c#?
>
> I tried to post this to the list yesterday but it bounced because of
> address issues...hopefully this will work:
>
> If you want to execute a python program from c-sharp you can just use
> System.Diagnostics.Process to execute python.exe and you don't need
> python for .net.
>
> Python for .net is more appropriate for if you want to execute a
python
> function or create an instance of a python object and then run methods
> and access attributes from your C# program.
>
> The example you linked to is OK, except that he modified the
> Python.Runtime.Dll which is not necessary.
>
> If you had a Hello.py with a function called hello Like this:
>
> def hello():
>     return 'hello'
>
>
> You could do this in C#:
>
> PythonEngine.Initialize();
> PyObject helloModule = PythonEngine.ImportModule("Hello");
> String fromPython = helloModule.InvokeMethod("hello", new
> PyTuple()).ToString(); PythonEngine.Shutdown();
>
> // now fromPython = "hello"
>
> If your function takes an argument:
>
> def returnArg(arg):
>     return arg
>
> PythonEngine.Initialize();
> PyObject helloModule = PythonEngine.ImportModule("Hello");
> String fromPython = helloModule.InvokeMethod("returnArg", new
> PyObject[1] {new PyString("Test")}).ToString();
PythonEngine.Shutdown();
>
> // now fromPython = "test"
>
> ________________________________
>
>         From: pythondotnet-bounces at python.org
> [mailto:pythondotnet-bounces at python.org] On Behalf Of Barrett, Joey
>         Sent: Tuesday, June 05, 2007 8:11 PM
>         To: pythondotnet at python.org
>         Subject: Re: [Python.NET] Could you tell me how to call python
> from c#?
>
>
>
>         Hi,
>
>
>
>         I also would be very interested in seeing some examples to
"call
> python from c#" using "Python for .NET".  I have dug around Google and
a
> number of forums---I can't find anything except the post from below.
I
> really hope I'm not missing the obvious somewhere.
>
>
>
>         IronPython is great but my needs require using a few c++
> extensions compiled for CPython (that can't be recompiled).
>
>
>
>         Also thanks in advance,
>
>
>
>         Joey J. Barrett
>
>         Investment Technology Group, Inc.
>
>
>
>
>
>
>
>
>
>         Hello, PythonNet!
>
>
>         I'm looking for some sample code to call python from C#.
>         Actually, I'd like to execute python program(let say
'Hello.py')
> from C#
>         with parameters.
>         Actually, I'm a newbie at both of languages. So, could you
give
> sample
>         source code? I was looking for some guide or source for
several
> days,
>         but I couldn't find it. What I've got so far from googling is
>
>
http://mail.python.org/pipermail/pythondotnet/2003-November/000037.html,
>
>         but I can't understand it and old one.
>
>         Thank you in advance.
>         Seungweon.
>
>
>
>
>
>
>
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> -+-
>         This message is for the named person's use only. This
> communication is for
>         informational purposes only and has been obtained from sources
> believed to
>         be reliable, but it is not necessarily complete and its
accuracy
> cannot be
>         guaranteed. It is not intended as an offer or solicitation for
> the purchase
>         or sale of any financial instrument or as an official
> confirmation of any
>         transaction. Moreover, this material should not be construed
to
> contain any
>         recommendation regarding, or opinion concerning, any security.
> It may
>         contain confidential, proprietary or legally privileged
> information. No
>         confidentiality or privilege is waived or lost by any
> mistransmission. If
>         you receive this message in error, please immediately delete
it
> and all
>         copies of it from your system, destroy any hard copies of it
and
> notify the
>         sender. You must not, directly or indirectly, use, disclose,
> distribute,
>         print, or copy any part of this message if you are not the
> intended
>         recipient.  Any views expressed in this message are those of
the
> individual
>         sender, except where the message states otherwise and the
sender
> is
>         authorized to state them to be the views of any such entity.
>
>         Securities products and services provided to Canadian
investors
> are offered
>         by ITG Canada Corp. (member CIPF and IDA), an affiliate of
> Investment
>         Technology Group, Inc.
>
>         ITG Inc. and/or its affiliates reserves the right to monitor
and
> archive
>         all electronic communications through its network.
>
>         ITG Inc. Member NASD, SIPC
>
>
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> -+-
>
>
> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
>
> This e-mail (including any attachments) may contain
> information that is private, confidential, or
> protected by attorney-client or other privilege.  If
> you received this e-mail in error, please delete it
> from your system without copying it and notify sender
> by reply e-mail, so that our records can be corrected.
>
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-+-
> This message is for the named person's use only. This communication is
for
> informational purposes only and has been obtained from sources
believed to
> be reliable, but it is not necessarily complete and its accuracy
cannot be
> guaranteed. It is not intended as an offer or solicitation for the
purchase
> or sale of any financial instrument or as an official confirmation of
any
> transaction. Moreover, this material should not be construed to
contain any
> recommendation regarding, or opinion concerning, any security. It may
> contain confidential, proprietary or legally privileged information.
No
> confidentiality or privilege is waived or lost by any mistransmission.
If
> you receive this message in error, please immediately delete it and
all
> copies of it from your system, destroy any hard copies of it and
notify the
> sender. You must not, directly or indirectly, use, disclose,
distribute,
> print, or copy any part of this message if you are not the intended
> recipient.  Any views expressed in this message are those of the
individual
> sender, except where the message states otherwise and the sender is
> authorized to state them to be the views of any such entity.
>
> Securities products and services provided to Canadian investors are
offered
> by ITG Canada Corp. (member CIPF and IDA), an affiliate of Investment
> Technology Group, Inc.
>
> ITG Inc. and/or its affiliates reserves the right to monitor and
archive
> all electronic communications through its network.
>
> ITG Inc. Member NASD, SIPC
>
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-+-
> _________________________________________________
> Python.NET mailing list - PythonDotNet at python.org
> http://mail.python.org/mailman/listinfo/pythondotnet
>
_________________________________________________
Python.NET mailing list - PythonDotNet at python.org
http://mail.python.org/mailman/listinfo/pythondotnet
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
This message is for the named person's use only. This communication is for
informational purposes only and has been obtained from sources believed to
be reliable, but it is not necessarily complete and its accuracy cannot be
guaranteed. It is not intended as an offer or solicitation for the purchase
or sale of any financial instrument or as an official confirmation of any
transaction. Moreover, this material should not be construed to contain any
recommendation regarding, or opinion concerning, any security. It may
contain confidential, proprietary or legally privileged information. No
confidentiality or privilege is waived or lost by any mistransmission. If
you receive this message in error, please immediately delete it and all
copies of it from your system, destroy any hard copies of it and notify the
sender. You must not, directly or indirectly, use, disclose, distribute,
print, or copy any part of this message if you are not the intended
recipient.  Any views expressed in this message are those of the individual
sender, except where the message states otherwise and the sender is
authorized to state them to be the views of any such entity.

Securities products and services provided to Canadian investors are offered
by ITG Canada Corp. (member CIPF and IDA), an affiliate of Investment
Technology Group, Inc.

ITG Inc. and/or its affiliates reserves the right to monitor and archive
all electronic communications through its network.

ITG Inc. Member NASD, SIPC
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-


More information about the PythonDotNet mailing list