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Re: HASH question [message #75449 is a reply to message #75367]

Tue, 08 March 2011 07:05

pgrigis
Messages: 436
Registered: September 2007

Senior Member

On Mar 7, 4:02 pm, Paulo Penteado <pp.pente...@gmail.com> wrote:
> On Mar 7, 5:32 pm, Paolo <pgri...@gmail.com> wrote:
>
>> Single stars can easily be located with where:
>
>> ind=where(allstars.starID EQ 'Delta Pavonis',count)
>> if count EQ 1 then print,'The magnitude of '+allstars[ind].starID+' is
>> '+strtrim(allstars[ind].magnitude,2)
>
> I would not call that "easily". The two problems are mentioned in the
> first question: "but I don't a priori know how many stars I have, and
> to find a particular star I'd have to search on the ID element."
>
> The search is awkward and not efficient,
well i never thought of "where" as being particularly awkward
inefficient, yes if used a lot
alternatively the stars could be sorted alphabetically by ID
to allow for fast search

> the arrays cannot have elements dynamically added or removed,

you can do concatenatation to add, say, another bunch of 100 stars
stars can be removed by setting the ID to the empty string or
using array concatenation yet again
not extremly efficient but works

> and they would not avoid
> repetitions (elements with the same key).
stars are unique - so why would he have duplicates?

Ciao,
Paolo

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[Message index]

		HASH question By: Gray on Sat, 05 March 2011 05:41
		Re: HASH question By: penteado on Tue, 08 March 2011 10:15
		Re: HASH question By: pgrigis on Tue, 08 March 2011 10:12
		Re: HASH question By: penteado on Tue, 08 March 2011 07:56
		Re: HASH question By: David Fanning on Tue, 08 March 2011 07:11
		Re: HASH question By: pgrigis on Tue, 08 March 2011 07:05
		Re: HASH question By: Gray on Tue, 08 March 2011 04:23
		Re: HASH question By: chris_torrence@NOSPAM on Mon, 07 March 2011 13:38
		Re: HASH question By: penteado on Mon, 07 March 2011 13:05
		Re: HASH question By: penteado on Mon, 07 March 2011 13:02
		Re: HASH question By: chris_torrence@NOSPAM on Mon, 07 March 2011 13:00
		Re: HASH question By: pgrigis on Mon, 07 March 2011 12:32
		Re: HASH question By: Jeremy Bailin on Mon, 07 March 2011 11:15

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