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Re: Null's not null?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg69406] Re: Null's not null?
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Mon, 11 Sep 2006 05:38:51 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <ee0t74$b5m$1@smc.vnet.net>

AES wrote:
> Putting Null into one or more slots in a Table and printing the Table 
> shows "Null" (without quotes) at the corresponding positions, as also 
> does ToString[Null].  I don't think that's what the Help message says:
> 
>       "Null is a symbol used to indicate the absence of an 
>        expression or a result. When it appears as an output 
>        expression, no output is printed."
> 
> I can use a string with a couple of empty spaces ("__") to represent an 
> occupied but not empty slot in a Table, but that just looks clumsy to 
> me.  Is there a truly non-printing Null symbol?
> 
What about using the \[Null] character [1], character that is not displayed?

Table[If[Random[] < 0.5, 1, \[Null]], {10}]

HTH,
Jean-Marc

[1] _The Mathematica Book_, Section 3.10.5 "Structural Elements and 
Keyboard Characters" 
http://documents.wolfram.com/mathematica/book/section-3.10.5


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