[scilab-Users] Random selection
Daniele Andreucci
andreucci at dmmm.uniroma1.it
Fri Dec 10 11:25:51 CET 2010
Carrico, Paul wrote on 12/10/10 10:27:
> Dear all,
>
> This is a strange idea (but usefull one) : I've a list a X point and I
> would like to select 3 of them in a random way (of course a point can be
> choose only ounce)
>
> I can use the following code
> round(X*rand(1,3))
>
> neverthless :
> - I've to loop until the 3 integer are different
> - if X becomes small it's diffucult to have 3 different values
>
> I'm sure these a simplier way to generate these 3 integers ... can I
> have an advice ?
>
> Thanks
>
> Paul
>
> --------------------------------------------------------------------------------
>
Dear Paul,
you are looking for a selection from a random permutation (since each
point can be selected once).
For example with
grand(1,"prm",a)
(a=column vector) you can proceed as follows:
-->X=10;
-->a=[1:X]'
a =
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
-->b=grand(1,"prm",a)
b =
2.
10.
1.
5.
4.
9.
8.
3.
7.
6.
-->myselection=b(1:3)
myselection =
2.
10.
1.
Daniele
--
[ Daniele Andreucci
[ Dip. di Scienze di Base e Applicate per l'Ingegneria
[ via A. Scarpa 16 00161 Roma, Italy
[ tel. +39 0649766785
[ fax +39 064957647
[ e-mail: andreucci at dmmm.uniroma1.it
[ http://www.dmmm.uniroma1.it/~andreucci/
[ gpg pub key id: D3ADC732
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 262 bytes
Desc: OpenPGP digital signature
URL: <https://lists.scilab.org/pipermail/users/attachments/20101210/db8c4d1d/attachment.sig>
More information about the users
mailing list