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MathGroup Archive 2004

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Re: Challenge: Fastest method to convert positive integers to 1 in a long list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52187] Re: Challenge: Fastest method to convert positive integers to 1 in a long list
  • From: bghiggins at ucdavis.edu (Brian Higgins)
  • Date: Sun, 14 Nov 2004 04:30:31 -0500 (EST)
  • References: <cn4m4e$19p$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

This is the best I could to:

seq = Table[Random[Integer, 10], {10^6}];

newseq = 1+Quotient[#,#+1,1]&@seq;//Timing

{0.16 Second,Null}

newseq2 =(If[#>0,1,0]&)/@seq;//Timing

{0.5 Second,Null}

Brian


"Carl K. Woll" <carlw at u.washington.edu> wrote in message news:<cn4m4e$19p$1 at smc.vnet.net>...
> Hi all,
> 
> Inspired by the recent thread on counting runs, I have the following 
> challenge. Come up with a method to convert all the positive integers in a 
> long sequence of nonnegative integers to 1, so that the sequence consists of 
> only 0s and 1s. Let the sequence be given by
> 
> seq = Table[Random[Integer, 10], {10^6}];
> 
> Then, one technique is
> 
> newseq = 1+Quotient[#,#+1,1]&@seq;
> 
> Can anyone do better?
> 
> Carl Woll


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