| Re: Sacrilegious but genuine question [message #28724] |
Wed, 09 January 2002 13:45  |
Mark Fardal
Messages: 51
Registered: October 1995
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Member |
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Andy Loughe <loughe@fsl.noaa.gov> writes:
> Mark Fardal wrote:
>> Just don't try doing it by yourself. ...
>
> Mmmm... maybe you should ask someone who has done it!
>
> http://nickbower.com/computer/pydl
Pydl does NOT give you "the functionality of IDL". It implements a
few commonly used IDL commands in Python. Probably 90% of all IDL
commands are missing, and those that are there are not necessarily
implemented completely. If you want to calculate and plot a few
things with a free package, without learning an entirely new syntax,
Pydl could be useful. If you want something as powerful as IDL, there
is a lot of work yet to be done.
Mark
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| Re: Sacrilegious but genuine question [message #28740 is a reply to message #28728] |
Wed, 09 January 2002 02:28  |
Nigel Wade
Messages: 286
Registered: March 1998
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Senior Member |
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Francis Burton wrote:
> How easy would it be to obtain the functionality of IDL by
> using Python as the underlying language glue, supplemented
> by hard-coded modules for image, signal & file processing,
> graphical I/O etc.? It seems that it can already do that in
> some problem domains - e.g. Python Imaging Library.
That might provide some functionality for image processing. But what about
all the other graphics/visualization capabilities of IDL? To emulate those
you need to find other Python add-ons, each with its own peculiarities,
build and install them, configure them to do what you want and maybe
they'll come somewhere near what IDL can do out of the box.
>
> Put another way: What are the advantages of IDL compared to
> such an open source framework?
Support and functionality
(unless you own a Mac - but we're not going there again are we?)
What do you do when the author of your favorite Python add-on gets bored
with Python and decides to go on to do something else?
--
-----------------------------------------------------------
Nigel Wade, System Administrator, Space Plasma Physics Group,
University of Leicester, Leicester, LE1 7RH, UK
E-mail : nmw@ion.le.ac.uk
Phone : +44 (0)116 2523568, Fax : +44 (0)116 2523555
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| Re: Sacrilegious but genuine question [message #28754 is a reply to message #28740] |
Tue, 08 January 2002 11:38 |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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"Liam E. Gumley" <Liam.Gumley@ssec.wisc.edu> writes:
> Francis Burton wrote:
>> How easy would it be to obtain the functionality of IDL by
>> using Python as the underlying language glue, supplemented
>> by hard-coded modules for image, signal & file processing,
>> graphical I/O etc.? It seems that it can already do that in
>> some problem domains - e.g. Python Imaging Library.
>
> http://nickbower.com/computer/pydl is a first cut.
>
>> Put another way: What are the advantages of IDL compared to
>> such an open source framework?
>
> It depends on what your goal is.
>
> If your goal is to read, analyze, and visualize data for the purpose of
> earning a living or obtaining a degree, then I'd use IDL.
>
> If your goal is to have fun writing new code for which you don't get
> paid or earn any credits, then I'd roll your own open source solution in
> Python (if you can get someone to pay you for it, well done).
I've thought about this kind of question before too. I think there is
another question:
If your need is to use one of the many library functions written in
IDL, either already available in the IDL distribution, or available on
the internet, then use IDL. Use and compatibility of existing
libraries is a huge issue for me.
Craig
--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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| Re: Sacrilegious but genuine question [message #28756 is a reply to message #28754] |
Tue, 08 January 2002 10:16 |
Liam E. Gumley
Messages: 378
Registered: January 2000
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Senior Member |
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Francis Burton wrote:
> How easy would it be to obtain the functionality of IDL by
> using Python as the underlying language glue, supplemented
> by hard-coded modules for image, signal & file processing,
> graphical I/O etc.? It seems that it can already do that in
> some problem domains - e.g. Python Imaging Library.
http://nickbower.com/computer/pydl is a first cut.
> Put another way: What are the advantages of IDL compared to
> such an open source framework?
It depends on what your goal is.
If your goal is to read, analyze, and visualize data for the purpose of
earning a living or obtaining a degree, then I'd use IDL.
If your goal is to have fun writing new code for which you don't get
paid or earn any credits, then I'd roll your own open source solution in
Python (if you can get someone to pay you for it, well done).
Cheers,
Liam.
Practical IDL Programming
http://www.gumley.com/
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| Re: Sacrilegious but genuine question [message #28815 is a reply to message #28727] |
Thu, 10 January 2002 02:15 |
Francis Burton
Messages: 11
Registered: October 2001
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Junior Member |
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Andy Loughe wrote:
>
> Mark Fardal wrote:
>>
>> Francis Burton <F.Burton@biomed.gla.ac.uk> writes:
>>
>>> How easy would it be to obtain the functionality of IDL by
>>> using Python as the underlying language glue, supplemented
>>> by hard-coded modules for image, signal & file processing,
>>> graphical I/O etc.?
>>
>> Not very easy. But easier than say, writing an open-source
>> operating system, and look what happened there...
>>
>> Just don't try doing it by yourself. The Numpy and SciPy mailing
>> lists are places to start. At least on the Numpy list, the topic of
>> IDL emulation and translation has come up recently.
>>
>> Mark
>
> Mmmm... maybe you should ask someone who has done it!
>
> http://nickbower.com/computer/pydl
Thank you for the pointer to PYDL, and to Liam Gumley who also
mentioned it a couple of days ago.
While I think it is interesting and worthwhile project, it is
really only a start (it's at version 0.1b2). It offers very
limited functionality, the documentation looks nice but is
riddled with errors, and some of the comments therein made me
wince a bit. E.g. talking about READ_ASCII "If you don't use
white-space delimiters, then use the UNIX command tr to create
a white-space delimited version. Live with it." There is no
reason why trivial misfeatures like that can't be fixed. And
they probably will be if enough people who care about quality
get involved.
What I think PYDL in its current state is valuable for is to
show what is possible. What I have seen so far is encouraging.
Let me make it clear that I have nothing against IDL - apart
from its high cost (putting it beyond the reach of individuals
like me), the irksome licensing issues, the uncertainty about
which platforms will be supported, the fact that it is rather
difficulty to add functionality of one's own (see below), and
its rather odd syntax (e.g. the comma between command name
and arguments). I =do= like its very respectable performance
and the fact that all the functionality is provided in a single
package - though I don't see why PYDL (or similar framework)
couldn't at some point be provided as a consolidated bundle.
I mentioned extensibility. What I would =really= like to be
able to do in IDL is have windows which allow much greater
interaction with plotted data. For instance, I have fairly
large (50,000-500,000 point) digitized signals which I would
like to 1) plot in an efficient manner (i.e. min-max for each
x pixel rather than drawing a line between every point) and
2) create and overlay various mousable widgets which return
values to IDL code. For example, I'd like to be able to click
an arbitrary number of points under the trace to define a
baseline for subtraction - and be able to adjust the position
of already defined nodes, but constrain them to be monotonically
increasing in x. In this case, the widget (if that is the right
name for it) would return a list of (x,y) values. Then the IDL
code could do the subtraction and replot the adjusted trace.
The trouble is that I have no idea how to do this in IDL. I'm
not even 100% sure that it is possible - at least, I believe
the effort required would be prohibitive. On the other hand,
a well designed framework of the type exemplified by PYDL
=could= make such extension quite easy.
Anyway enough rambling. Thanks to everyone who responded.
Francis
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| Re: Sacrilegious but genuine question [message #28819 is a reply to message #28756] |
Wed, 09 January 2002 18:55 |
rmw092001
Messages: 17
Registered: January 2002
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Junior Member |
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"Liam E. Gumley" <Liam.Gumley@ssec.wisc.edu> wrote in message news:<3C3B378C.F85C497E@ssec.wisc.edu>...
> Francis Burton wrote:
>> How easy would it be to obtain the functionality of IDL by
>> using Python as the underlying language glue, supplemented
>> by hard-coded modules for image, signal & file processing,
>> graphical I/O etc.? It seems that it can already do that in
>> some problem domains - e.g. Python Imaging Library.
>
> http://nickbower.com/computer/pydl is a first cut.
>
>> Put another way: What are the advantages of IDL compared to
>> such an open source framework?
>
> It depends on what your goal is.
>
> If your goal is to read, analyze, and visualize data for the purpose of
> earning a living or obtaining a degree, then I'd use IDL.
>
> If your goal is to have fun writing new code for which you don't get
> paid or earn any credits, then I'd roll your own open source solution in
> Python (if you can get someone to pay you for it, well done).
>
> Cheers,
> Liam.
> Practical IDL Programming
> http://www.gumley.com/
It's a pity RSI don't make a decent, inexpensive 'IDL Limited Edition'
- just file read/writing, numbercrunching, plotting etc - no widgets,
object graphics or industrial stuff. IDL 'student edition' restricts
array sizes so much it's almost useless. If pydl effectively becomes
IDL-LE, that would be great.
Richard
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