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MathGroup Archive 1998

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Re: List Manipulation


  • To: mathgroup@smc.vnet.net
  • Subject: [mg10494] Re: List Manipulation
  • From: "Stephen P Luttrell" <luttrell@signal.dra.hmg.gb>
  • Date: Tue, 20 Jan 1998 02:22:44 -0500
  • Organization: Defence Evaluation and Research Agency
  • References: <69nbfq$89h@smc.vnet.net>

>  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.


Try this example

a=Table[i+j,{i,4},{j,2}]
b=Partition[a,2]
c=Map[#[[1]]&,b]

which gives the required output

{{2,3},{3,4},{4,5},{5,6}}

{{{2,3},{3,4}},{{4,5},{5,6}}}

{{2,3},{4,5}}

=======================================================

Stephen P Luttrell
luttrell@signal.dra.hmg.gb
Adaptive Systems Theory                           01684-894046 (phone)
Room EX21, DERA                                    01684-894384 (fax)
Malvern, Worcs, WR14 3PS, U.K.
http://www.dra.hmg.gb/cis5pip/Welcome.html





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