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MathGroup Archive 1998

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Re: List Manipulation


  • To: mathgroup@smc.vnet.net
  • Subject: [mg10594] Re: List Manipulation
  • From: Daniel Lichtblau <danl@wolfram.com>
  • Date: Mon, 26 Jan 1998 04:42:25 -0500
  • Organization: Wolfram Research, Inc.
  • References: <69nbfq$89h@smc.vnet.net>

Paul.Hanson@colorado.edu wrote:
> 
> Hola!
>   Hope you're all doing well.  If I have a list of n lists, and want to
> get rid of all the even ones how would I go about doing  this?  That
> is, {{n1},{n2},.....{2n}} converted to {{n1},{n3}...{2n-1}}. I tried
> using the various procedures in Wolfram's book, but nothing seems to
> work (ie, Delete, Take, etc.).  Thanks for the help.
> 
> Paul Hanson
> 
> --
>                                  * *
>                                 *    *
>                            /\    */\*
>                           /  \   /  \ /\


One efficient way is to create a new list with Table.

list = {{a},{b,c},{d},{e,f,g},{h,a},{k,l,{m,n}},{o,p,q}};

In[6]:= Table[list[[2*j-1]], {j,Quotient[Length[list]+1,2]}] Out[6]=
{{a}, {d}, {h, a}, {o, p, q}}

or

In[7]:= Table[list[[j]], {j,1,Length[list],2}] Out[7]= {{a}, {d}, {h,
a}, {o, p, q}}


Daniel Lichtblau
Wolfram Research



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