comp.lang.idl-pvwave archive: archive » Re: remove duplicates WITHOUT sorting

Home » Public Forums » archive » Re: remove duplicates WITHOUT sorting

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: remove duplicates WITHOUT sorting [message #52686 is a reply to message #52557]

Wed, 14 February 2007 07:32

Vince Hradil
Messages: 574
Registered: December 1999

Senior Member

On Feb 13, 9:18 am, "rpert...@gmail.com" <rpert...@gmail.com> wrote:
> On Feb 12, 4:15 pm, JD Smith <jdsm...@as.arizona.edu> wrote:
>
>
>
>> On Mon, 12 Feb 2007 09:04:45 -0800, rpert...@gmail.com wrote:
>>> Hello All,
>>> I have an array of 2xn which is a list of coordinates (x,y positions)
>>> and I need to remove any duplicates in this array. Since they are x,y
>>> coordinates I cannot really sort the array, hence cannot use the Uniq
>>> function. Is there another way of doing this?
>
>> It's easiest to recast as 1D. HIST_2D (or HIST_ND) does this for you, but
>> it's easy to do yourself:
>
>> index=x + (max(x)+1)*y
>
>> and then using UNIQ on this list of indices should give you the row
>> positions of unique coordinates. HISTOGRAM can work as well (either
>> with HIST_ND, or by first constructing this index vector above), and
>> it will be faster, but, as usual, will consume lots of memory (and
>> potentially be very slow) if your coordinates are sparsely sprinkled over
>> a large range of values (your current example is somewhat sparse, but not
>> horrible). UNIQ, with its SORT based implementation, doesn't suffer from
>> that issue.
>
>> JD
>
> Thank You All for responding.
> I basically did sort in the end, but sorted the x coords and
> corresponding y coords stayed with
> its pair. Then did a shift to eliminate recurrences:
>
> SortIndex=Sort(AllCoords[0,*])
> for j=0,1 Do AllCoords[j,*] = AllCoords[j,sortindex]
> Print,"Sorted All Cords is",AllCoords
> print,' '
>
> B=AllCoords - Shift(AllCoords,2)
> print,' '
> C=AllCoords[*,where(B[0,*] ge 0.5 or B[1,*] ge 0.6)]
> csize=size(C,/dimensions)
> print,'size c' ,csize[0],csize[1]

So did you try the cast-to-complex, recast-to-float approach?

Report message to a moderator

[Message index]

		Re: remove duplicates WITHOUT sorting By: Jean H. on Tue, 13 February 2007 08:10
		Re: remove duplicates WITHOUT sorting By: rpertaub@gmail.com on Tue, 13 February 2007 07:18
		Re: remove duplicates WITHOUT sorting By: JD Smith on Mon, 12 February 2007 13:15
		Re: remove duplicates WITHOUT sorting By: btt on Mon, 12 February 2007 11:23
		Re: remove duplicates WITHOUT sorting By: Brian Larsen on Mon, 12 February 2007 10:38
		Re: remove duplicates WITHOUT sorting By: David Fanning on Mon, 12 February 2007 09:38
		Re: remove duplicates WITHOUT sorting By: Vince Hradil on Mon, 12 February 2007 09:23
		Re: remove duplicates WITHOUT sorting By: Craig Markwardt on Mon, 12 February 2007 09:23
		Re: remove duplicates WITHOUT sorting By: Vince Hradil on Wed, 14 February 2007 07:32

Previous Topic:	Cannot resolve QUERY_JPEG
Next Topic:	Re: Writing to the IDLde

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 19:58:21 PDT 2025

Total time taken to generate the page: 0.00407 seconds