Re: Selecting Lists Without Null Results
- To: mathgroup at smc.vnet.net
- Subject: [mg69022] Re: [mg68970] Selecting Lists Without Null Results
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Sun, 27 Aug 2006 01:23:42 -0400 (EDT)
- Reply-to: hanlonr at cox.net
- Sender: owner-wri-mathgroup at wolfram.com
runsTable=Table[Random[],{5},{6}]; runsTable[[2,4]]=Null; runsTable[[4,4]]=Null; Length[Select[runsTable, #[[4]] == Null&]] 2 Length[Select[runsTable, ToString[#[[4]]] != "Null"&]] 3 Bob Hanlon ---- Gregory Lypny <gregory.lypny at videotron.ca> 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 >