| Re: matching coordinates [message #55065 is a reply to message #55062] |
Mon, 30 July 2007 04:12   |
jradavenport
Messages: 6
Registered: July 2007
|
Junior Member |
|
|
On Jul 30, 4:36 am, jradavenp...@gmail.com wrote:
> On Jul 29, 7:53 am, David Fanning <n...@dfanning.com> wrote:
>
>
>
>> jradavenp...@gmail.com writes:
>>> Hello, I'm a long time lurker of this group, and finally have a
>>> problem I can't solve efficiently enough! I have coordinates for stars
>>> (RA and DEC for us astronomers out there), from two sources. i.e.
>>> (x1,y1) and (x2,y2). These lists are huge, like 150k for one and
>>> 5million in the other (a lot of stars!). I need to find the matches
>>> from these catalogs within a tolerance. I've tried a few programs
>>> I've found online (close_match_radec for instance) and they have not
>>> given me results I believe (multiple matches and such). Here is some
>>> horrible code I wrote just now which solves the problem VERY slowly:
>
>> Here is an article that might help:
>
>> http://www.dfanning.com/code_tips/matchlists.html
>
>> For background, you might want to read the precursor
>> article, and one of my personal favorites:
>
>> http://www.dfanning.com/code_tips/slowloops.html
>
>> Cheers,
>
>> David
>> --
>> David Fanning, Ph.D.
>> Fanning Software Consulting, Inc.
>> Coyote's Guide to IDL Programming:http://www.dfanning.com/
>> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
>
> Thanks David, Big fan of your site and of yours and JD Smith's code...
> I guess it really is time to learn that Histogram function (something
> I've put off for over a year!)
>
> I'm turning that example code into a workable program, but am confused
> on where the results are. Which Variable do I want to return with the
> answers?
Actually, scratch that. I believe it's the min_pos and min_dist
variables. The only other problem I'm having is it's telling me in
line 40 (including a program begin line)
% HISTOGRAM: Illegal binsize or max/min.
This is for the line:
;; Dual HISTOGRAM method, loop by repeat count in bins
h2 = histogram(h[b],MIN=1,REVERSE_INDICES=ri2)
Anybody have ideas who knows about Histogram?
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
