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MathGroup Archive 2006

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Selecting Lists Without Null Results

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68970] Selecting Lists Without Null Results
  • From: Gregory Lypny <gregory.lypny at videotron.ca>
  • Date: Sat, 26 Aug 2006 02:03:52 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

	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


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