| Re: Python and IDL [message #39565] |
Fri, 28 May 2004 14:01 |
![Chris[1] is currently offline](theme/default/images/xoffline.png.pagespeed.ic.XRkd1fkXye.png "Chris[1] is currently offline")
Chris[1]
Messages: 23
Registered: January 2003
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Junior Member |
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Actually, rather than using Python to create the FIFO, you can use IDL
(using the "spawn,'mkfifo filename' " command)
Chris
"Chris" <not@this.address> wrote in message
news:hGNtc.38188$sr3.1238798@news20.bellglobal.com...
> Are you writing on a Unix-based system? Then you can use Python (I assume)
> to open a fifo; pass the name to the IDL routine, and have IDL open it as
a
> simple file using openu (open for update). I've found this a really
> efficient way to have IDL processes communicate on a multi-processor
system,
> since the Linux OS handles all the communications issues; and our
efficiency
> scaled nicely with the number of processors. If you want to be more
general,
> you could probably go to using sockets at both levels (I think the socket
> protocol is also available in windoze. I tried the pipe operations
available
> on W2K, all I can say is that it was up to the usual MS standards).
>
> Chris
>
> "Michael Wallace" <mwallace.no.spam@no.spam.swri.edu.invalid> wrote in
> message news:10ben71fnpegs2f@corp.supernews.com...
>> I'm probably the only person here who'd be interested in this, but I
>> guess I'll throw it out anyway.
>>
>
>
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| Re: Python and IDL [message #39566 is a reply to message #39565] |
Fri, 28 May 2004 13:55  |
Chris[1]
Messages: 23
Registered: January 2003
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Junior Member |
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Are you writing on a Unix-based system? Then you can use Python (I assume)
to open a fifo; pass the name to the IDL routine, and have IDL open it as a
simple file using openu (open for update). I've found this a really
efficient way to have IDL processes communicate on a multi-processor system,
since the Linux OS handles all the communications issues; and our efficiency
scaled nicely with the number of processors. If you want to be more general,
you could probably go to using sockets at both levels (I think the socket
protocol is also available in windoze. I tried the pipe operations available
on W2K, all I can say is that it was up to the usual MS standards).
Chris
"Michael Wallace" <mwallace.no.spam@no.spam.swri.edu.invalid> wrote in
message news:10ben71fnpegs2f@corp.supernews.com...
> I'm probably the only person here who'd be interested in this, but I
> guess I'll throw it out anyway.
>
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| Re: Python and IDL [message #39567 is a reply to message #39566] |
Fri, 28 May 2004 13:43 |
JD Smith
Messages: 850
Registered: December 1999
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Senior Member |
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On Fri, 28 May 2004 10:38:08 -0500, Michael Wallace wrote:
> I'm probably the only person here who'd be interested in this, but I guess
> I'll throw it out anyway.
>
> I have recently started using Python and love the language. Python is
> interpreted, interactive, object oriented, and has dynamic data types and
> dynamic typing. From this perspective, IDL and Python are very similar.
> There are even projects such as SciPy (http://www.scipy.org) which add
> some scientific analysis to the language.
>
> Python does have a couple nice benefits, namely the huge number of modules
> available where there's everything from operating system commands to
> networking to XML to email etc. One thing I've found myself doing
> recently is writing my core analysis processing code in IDL and then
> writing a Python wrapper around the particular code. For example, in one
> of my programs, I use Python to automatically download files from an FTP
> site and then call IDL to do the specific processing on the files. In
> another program, I use Python to process command line arguments and then
> call the appropriate IDL code based on the arguments.
>
> Currently, in my Python programs I open a pipe to an IDL process and write
> the IDL commands to the pipe. What I'm wondering is if there is an
> efficient way to send data from IDL back to Python. The only thing I've
> found so far is to have IDL write data to stdout and set up the Python
> side to read this stream. However, this can get pretty inefficient at
> times. Without any direct conversion between the two languages available,
> are there any other (i.e. better, efficient) ways to set up bi-directional
> interprocess communication between Python and IDL?
>
> What'd be really nice is if RSI provided some mechanism for IDL and Python
> to communicate at a much closer level than interprocess communication.
> Karl, that's a hint. ;-)
Seems like this one is coming up a bit recently: you could use shared
memory. This is typically the fastest IPC available, but does require
some coordination when both sides are reading & writing. It's also
fairly flexible, in that data in any format can be written. Actually
interpreting that data on the Python or IDL side would require the
same tricks implicit in writing DLMs (map integers to shorts, etc.),
but without needing to compile. Ideally you could write a glue module
which used shared memory to map arrays to arrays, etc.
JD
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| Re: Python and IDL [message #39569 is a reply to message #39567] |
Fri, 28 May 2004 09:12 |
marc schellens[1]
Messages: 183
Registered: January 2000
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Senior Member |
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Probably one could write a python wrapper for CALL_EXTERNAL or a DLM.
Note that GDL (http://gnudatalanguage.sourceforge.net) has an interface
to python.
marc
Michael Wallace wrote:
> I'm probably the only person here who'd be interested in this, but I
> guess I'll throw it out anyway.
>
> I have recently started using Python and love the language. Python is
> interpreted, interactive, object oriented, and has dynamic data types
> and dynamic typing. From this perspective, IDL and Python are very
> similar. There are even projects such as SciPy (http://www.scipy.org)
> which add some scientific analysis to the language.
>
> Python does have a couple nice benefits, namely the huge number of
> modules available where there's everything from operating system
> commands to networking to XML to email etc. One thing I've found myself
> doing recently is writing my core analysis processing code in IDL and
> then writing a Python wrapper around the particular code. For example,
> in one of my programs, I use Python to automatically download files from
> an FTP site and then call IDL to do the specific processing on the
> files. In another program, I use Python to process command line
> arguments and then call the appropriate IDL code based on the arguments.
>
> Currently, in my Python programs I open a pipe to an IDL process and
> write the IDL commands to the pipe. What I'm wondering is if there is
> an efficient way to send data from IDL back to Python. The only thing
> I've found so far is to have IDL write data to stdout and set up the
> Python side to read this stream. However, this can get pretty
> inefficient at times. Without any direct conversion between the two
> languages available, are there any other (i.e. better, efficient) ways
> to set up bi-directional interprocess communication between Python and IDL?
>
> What'd be really nice is if RSI provided some mechanism for IDL and
> Python to communicate at a much closer level than interprocess
> communication. Karl, that's a hint. ;-)
>
> -Mike
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