Re: array cross sections

[Geraint Paul Bevan]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Sean Smith wrote:
| Anybody know how to get a sub array of elements that meet some
criteria, or
| a sub matrix, or conditioned on some other array?
| I am looking for something that sort of works like grep in perl.
|
| The only thing I can think of right now is a complecated system of sorting
| and truncating that I would like to avoid.
|
| Thanks,
| Sean
|

Have a look at the 'find' function. You can use it to extract elements
which meet some criteria. For example, to get all the elements of a 3x3
matrix which are less than 0.5:

octave> a = rand (3,3)
a =

~  0.81472  0.83501  0.91338
~  0.13548  0.12699  0.22103
~  0.90579  0.96887  0.63236

octave> [i,j,v] = find (a .* (a<0.5))
i =

~  2
~  2
~  2

j =

~  1
~  2
~  3

v =

~  0.13548
~  0.12699
~  0.22103


- --
Geraint Bevan
http://homepage.ntlworld.com/geraint.bevan

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (GNU/Linux)

iEYEARECAAYFAkErjnIACgkQcXV3N50QmNNmHQCfXzw88bZhg7SOcSCVyUr2aOmE
g7sAniB0j0bsDSMLOIClc/A3SGbSRrof
=bGe5
-----END PGP SIGNATURE-----



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------