| Re: Where vs Histogram vs ?? [message #32593 is a reply to message #32526] |
Mon, 21 October 2002 17:59   |
Andrew Cool
Messages: 219
Registered: January 1996
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Senior Member |
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Hi Pavel,
"Pavel A. Romashkin" wrote:
>
> Allright, so we need a solution in IDL.
> At this array size the slowest portion of the process is not the WHERE
> function as far as I can tell. It is memory reallocation for the main
> array and for the temporary index arrays that IDL creates. Therefore I
> can suggest trying the following approach.
> Allocate it all only once:
>
> ind = ptrarr(n_tags(data_St)
Should this be something like
ind = ptrarr(N_Tags(data_st) * 15425228L)
given that N_Tags(data_st) only returns a value of 9, which concurs
with Tag_Names(data_st), such that we effectively have
ind = ptrarr(9 * 15425228L)
Now that's a scary sized ptrarr.
Given that you say :-
> On my machine the RAM used by both structure and pointer index barely
> reaches 1010 Mb, so I have room for further calculations.
and assuming you've used the figure of 15425228, then I obviously
don't
understand your example... ;-)
Would you mind elaborating a bit, in words of one brain cell or less?
Thanks,
Andrew
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Andrew D. Cool
Electromagnetics & Propagation Group
Intelligence, Surveillance & Reconnaissance Division
Defence Science & Technology Organisation
PO Box 1500, Edinburgh
South Australia 5111
Phone : 061 8 8259 5740 Fax : 061 8 8259 6673
Email : andrew.cool@no-spam.dsto.defence.gov.au
Please remove the no-spam from my email address to reply.
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