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Re: null array [message #36478 is a reply to message #36472]

Wed, 24 September 2003 09:17

JD Smith
Messages: 850
Registered: December 1999

Senior Member

On Tue, 23 Sep 2003 20:21:44 -0700, Reimar Bauer wrote:

> Tomson wrote:
>
>> Hi, I need a null array without any elements in it. Then elements will
>> be added to it. But how to define a null array?
>>
>> Best
>> Tomsom
>
> What is this? I don't use matlab.
>
> Would you like to do something like this.
>
> if n_elements(array) eq 0 then array=scalar else array=[array,scalar]
>
> Or in a loop
>
> for i=0,10 do begin
> ..
>
> if i eq 0 then array=scalar else array=[array,scalar] endfor
>
> Reimar

But this is also slow, since you reallocate the array on each iteration
(which starts to hurt when the array gets large). Far better is to
pre-allocate the array to roughly the correct size, and grow it as
necessary. Search this newsgroup for "Is there a standard 'null' array"
for a thread on this very topic.

JD

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[Message index]

		Re: null array By: David Fanning on Wed, 24 September 2003 18:35
		Re: null array By: tomson on Wed, 24 September 2003 17:47
		Re: null array By: JD Smith on Wed, 24 September 2003 09:17
		Re: null array By: R.Bauer on Wed, 24 September 2003 08:11
		Re: null array By: Paul Van Delst[1] on Wed, 24 September 2003 06:52
		Re: null array By: Ben Panter on Wed, 24 September 2003 02:08
		Re: null array By: Ben Panter on Wed, 24 September 2003 01:33
		Re: null array By: R.Bauer on Tue, 23 September 2003 20:21
		Re: null array By: David Fanning on Tue, 23 September 2003 20:04
		Re: null array By: David Fanning on Fri, 26 September 2003 02:24
		Re: null array By: Stein Vidar Hagfors H[2] on Tue, 30 September 2003 12:36

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