Re: Part
- Subject: [mg2897] Re: Part
- From: jorma.virtamo at vtt.fi (Jorma Virtamo)
- Date: 9 Jan 1996 04:25:29 -0600
- Approved: usenet@wri.com
- Distribution: local
- Newsgroups: wri.mathgroup
- Organization: Wolfram Research, Inc.
- Sender: mj at wri.com
wagner at bullwinkle.cs.Colorado.EDU (Dave Wagner) wrote: >In article <4cgrsc$im4 at dragonfly.wri.com>, >Hans Steffani <hans.steffani at e-technik.tu-chemnitz.de> wrote: >>w={{1,2,3},{4,5,6},{7,8,9}} >>npos={2,1} >> >>npos is the position of the element I need. >> >>w[[npos]] >> >>does not work, as it returns the second and the first >>line. > >This same question came up a couple of weeks ago. You want >to use: > > w[[Sequence @@ npos]] > >Sequence is an undocumented function that obliterates the head >of whatever it is applied to. In this case, it obliterates the >List wrapper, leaving a sequence of two integers. > Alternatively, one can write without using an undocumented function: w[[##]]& @@ npos -- Jorma Virtamo ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jorma Virtamo VTT Information Technology phone: +358 0 456 5612 Telecommunications fax: +358 0 455 0115 P.O. Box 1202 email: jorma.virtamo at vtt.fi FIN-02044 VTT web: http://www.vtt.fi/tte/ Finland