comp.lang.idl-pvwave archive: archive » Re: Avoiding loop stats

Home » Public Forums » archive » Re: Avoiding loop stats

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

Re: Avoiding loop stats [message #52149 is a reply to message #52144]

Fri, 19 January 2007 12:26

Foldy Lajos
Messages: 268
Registered: October 2001

Senior Member

On Fri, 19 Jan 2007, yp wrote:

> IDL Gurus,
> There is perhaps a smart solution to this problem, but I could not
> figure out.
> I have a series of EO images (2D) stacked over time which makes the
> data a 3D array of [4000, 2000, 900] i.e., [lon,lat,time]
> I need to compute various statistical parameters at each pixel over
> time and produce each of them as [4000,2000] array.
>
>
> for i=0,4000L-1 do for j=0,2000L-1 do data_st(i,j)=st_func(data(i,j,*))
>
> where, data=FLTARR[4000,2000,900]
> data_st is the output from a function 'st_func' which works with vector
> data only.
>
> Is there a way to do this avoiding the 4000x2000 loop? It is painfully
> slow on windows.
> thanks in advance
>

Some speedup can be achieved with optimized memory access (if you have
enough memory for two copies of data):

temp=transpose(data, [2,0,1])
for j=0l,2000l-1 do for i=0l,4000l-1 do data_st[i,j]=st_func(temp[*,i,j])

regards,
lajos

Report message to a moderator

[Message index]

		Re: Avoiding loop stats By: Jean H. on Mon, 22 January 2007 09:20
		Re: Avoiding loop stats By: MarioIncandenza on Mon, 22 January 2007 08:29
		Re: Avoiding loop stats By: Foldy Lajos on Fri, 19 January 2007 12:26
		Re: Avoiding loop stats By: yp on Fri, 19 January 2007 19:07
		Re: Avoiding loop stats By: news.qwest.net on Fri, 19 January 2007 12:00
		Re: Avoiding loop stats By: JD Smith on Fri, 19 January 2007 10:11

Previous Topic:	nicing idl at startup from idlwave
Next Topic:	ascii value of a char

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Fri Oct 10 12:48:32 PDT 2025

Total time taken to generate the page: 1.27978 seconds