Python script and C++

[Thuan Seah Tan]

Hi all,

I am new to python and currently I am working on a traffic simulation
which I plan to define the various agents using scripting. It's kind of like
scripting for non-playable character in games. I am thinking of using python
for this but I am concerned with running time. Is scripting a lot slower
compared to direct implementation in C++? Does compiling the script help in
any way? Also, can anyone recommend me a book that covers python in general
as well as C++ binding? Thanks.


Thuan Seah Tan

[nepBabu.cx]

Re: Python script and C++

Thuan Seah Tan wrote:

Hi all,
>
I am new to python and currently I am working on a traffic simulation
which I plan to define the various agents using scripting. It's kind of like
scripting for non-playable character in games. I am thinking of using python
for this but I am concerned with running time. Is scripting a lot slower
compared to direct implementation in C++? Does compiling the script help in

"Learning Python" is a good book to start learning Python. I don't think
you'll be better off in C++. If speed is of utmost importance for the
whole implementation, then I suggest C++ but well coded Python runs
atleast/near to C++ implementation. Otherwise, you can atleast code the
speed-savvy part of the implementation in C++. Ofcourse, Python object
model is based on a virtual machine (called PVM) which accounts for
slower start-up due to native function call conversion but you'll find
that learning curve is only a tiny fraction compared to C++. And you'll
surely love Python. =)

any way? Also, can anyone recommend me a book that covers python in general
as well as C++ binding? Thanks.

"Progamming in Python" is another excellent book that might be of help.
If you are developing on windows machine then
http://aspn.activestate.com/ASPN/Python has some helpful recipes.

C++ bindings in Python are handled by extending python objects and
manipulating it from C++ codes using the Python headers.

Also, http://python.org/docs should be a good reference.
Also Google for "vaults of parnassus" and Fredrik lundh's guide on Python.

Goodluck!


--
thanks,
nepBabu.cx
c c
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[George Sakkis]

Re: Python script and C++

Thuan Seah Tan wrote:

Hi all,
>
I am new to python and currently I am working on a traffic simulation
which I plan to define the various agents using scripting. It's kind of like
scripting for non-playable character in games. I am thinking of using python
for this but I am concerned with running time. Is scripting a lot slower
compared to direct implementation in C++? Does compiling the script help in
any way? Also, can anyone recommend me a book that covers python in general
as well as C++ binding? Thanks.

Even if pure python turns out to be slow for some critical parts of
your application, there are quite a few ways to deal with it: psyco,
pyrex, weave/blitz, ctypes, SWIG, Boost-python, SIP, CXX, SCXX,
hand-written C extensions and perhaps more. Visit
http://www.scipy.org/PerformancePython for an example of taking a
simple pure Python function and boosting it using several different
tools. Check out the final comparison table first; the pyrex version is
less than half a second slower than the C++.

George

[Ravi Teja]

Re: Python script and C++

Thuan Seah Tan wrote:

Hi all,
>
I am new to python and currently I am working on a traffic simulation
which I plan to define the various agents using scripting. It's kind of like
scripting for non-playable character in games. I am thinking of using python
for this but I am concerned with running time. Is scripting a lot slower
compared to direct implementation in C++? Does compiling the script help in
any way?

Python is perfectly suitable for this use. Python was in use in video
games in this way when computers were a lot slower. I doubt that you
will need to bother compiling the script or see any observable
enhancement if you do.

One example I can remember is Kingdom Under Fire (2001).

[Marc 'BlackJack' Rintsch]

Re: Python script and C++

In <1164691472.172 783.151290@n67g 2000cwd.googleg roups.com>, Ravi Teja
wrote:

> I am new to python and currently I am working on a traffic simulation
>which I plan to define the various agents using scripting. It's kind of like
>scripting for non-playable character in games. I am thinking of using python
>for this but I am concerned with running time. Is scripting a lot slower
>compared to direct implementation in C++? Does compiling the script help in
>any way?

>
Python is perfectly suitable for this use. Python was in use in video
games in this way when computers were a lot slower.

There's a difference between simulations and games. The simulation will
not always be observed by a human being so it runs as fast as possible.
In games the speed of NPCs is usually limited to a level the player can
deal with.

But I think Python is fine for such a task. The only way to find out if
it may be to slow is writing a prototype and measure. Maybe it's a good
idea to design the API for the "NPCs" independent from the language so you
can also write them in C++ or another scripting language.

Ciao,
Marc 'BlackJack' Rintsch

[Jorgen Grahn]

Re: Python script and C++

On Tue, 28 Nov 2006 10:12:23 +0100, Marc 'BlackJack' Rintsch <bj_666@gmx.net wrote:

In <1164691472.172 783.151290@n67g 2000cwd.googleg roups.com>, Ravi Teja
wrote:
>

>> I am new to python and currently I am working on a traffic simulation
>>which I plan to define the various agents using scripting. It's kind of like
>>scripting for non-playable character in games. I am thinking of using python
>>for this but I am concerned with running time. Is scripting a lot slower
>>compared to direct implementation in C++? Does compiling the script help in
>>any way?

>>
>Python is perfectly suitable for this use. Python was in use in video
>games in this way when computers were a lot slower.

>
There's a difference between simulations and games. The simulation will
not always be observed by a human being so it runs as fast as possible.
In games the speed of NPCs is usually limited to a level the player can
deal with.

Yeah. Simulation can mean running for a week on the best hardware available,
with the most optimized code you can come up with. And a week may be
acceptable, while two weeks are not.

But I think Python is fine for such a task.

I am not so sure, but ...

The only way to find out if
it may be to slow is writing a prototype and measure.

.... this is a good approach.

Maybe it's a good
idea to design the API for the "NPCs" independent from the language so you
can also write them in C++ or another scripting language.

However, if that API requires thousands of calls per second during
simulation time, it doesn't help speed much, because calling C code from
Python is a pretty heavy thing in itself. The big win is when you spend a
lot of uninterrupted CPU time in C code.

One approach is to write the executive engine in C++ (once again: if needed)
and the compiler/configuration subsystem -- the thing that generates the
simulated world -- in Python. That's a perfect place for a flexible,
high-level language.

/Jorgen

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