Re: Subsetting indexed variable?
- To: mathgroup at smc.vnet.net
- Subject: [mg36041] Re: [mg36028] Subsetting indexed variable?
- From: BobHanlon at aol.com
- Date: Wed, 14 Aug 2002 05:35:09 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 8/13/02 6:41:17 AM, gjr2008 at columbia.edu writes:
>I cannot seem to work out how to extract a subset of information from an
>indexed variable (without generating a full list/matrix first).
>
>For example, suppose I define:
>
>b[1,3] = 3
>b[2,3] = 7
>b[2,4] = 5
>
>And I then want to get the list of all DEFINED values of b[2,_], i.e.,
>the
>result should be {7,5}
Cases[DownValues[b], b[2, _], Infinity]
Bob Hanlon
Chantilly, VA USA