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MathGroup Archive 2007

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Re: Passing a list as seperate parameters?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg73222] Re: Passing a list as seperate parameters?
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Thu, 8 Feb 2007 03:34:33 -0500 (EST)
  • Organization: The Open University, Milton Keynes, UK
  • References: <eqc71p$qs7$1@smc.vnet.net>

Azumanga wrote:
> I have a recuring problem in using mathematica, which I'm sure there
> must be a simple fix for, but I've looked through the manual and can't
> find it.
> 
> As an example, I build up the list { {a,b},{c,d} }, and I want to find
> the union of it's elements.
> 
> At first glance, I want Union. However, Union wants it's input as
> Union[{a,b},{c,d}], Union[{{a,b},{c,d}}] doesn't do anything.
> 
> In general I get around this by fold, but it seems there should be a
> simpler method?
> 
> 
Change the head of the outermost list to Sequence. For example,

In[1]:=
lst = {{a, b}, {c, d}, {a, c, e}};
Union[Sequence @@ lst]

Out[2]=
{a, b, c, d, e}

Regards,
Jean-Marc


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