Re: Selecting Lists Without Null Results
- To: mathgroup at smc.vnet.net
- Subject: [mg69029] Re: Selecting Lists Without Null Results
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Sun, 27 Aug 2006 01:23:55 -0400 (EDT)
- References: <ecooe1$2qr$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi, Not[] acts on boolean expressions but you mean NotEqual[] .. And runsTable /. Null:> Sequence[] may do the same without any explicit usage of a test. And Null is a Mathematics Symbol and not a word like "Null". Regards Jens Gregory Lypny wrote: > I must be doing something wrong as usual. How come I can select > list with elements that have the word Null in them as a result of a > computation, but I cannot exclude them? > > I have an array called runsTable with 179 rows, and there are five > rows with Null in column 14. > > So, > > Length[Select[runsTable, #[[14]] == Null &] > > returns 5. > > But > > Length[Select[runsTable, (#[[14]]¬ Null) &]] > > returns 0 when it should return 174, that is, 179 minus 5. > > Am I using the NOT operator incorrectly? > > Regards, > > Gregory >