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MathGroup Archive 2002

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Re: help on bootstrap sample

  • To: mathgroup at smc.vnet.net
  • Subject: [mg37368] Re: [mg37338] help on bootstrap sample
  • From: Daniel Lichtblau <danl at wolfram.com>
  • Date: Fri, 25 Oct 2002 02:47:21 -0400 (EDT)
  • References: <200210240655.CAA05072@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Søren Merser wrote:
> 
> Hi Mathematica freeks
> I've made two small rutines for sampling (bootstrap statistics)
> They are working , but at least 'SampleNoReplace' is rather slow
> I was wondering if any of you know of a faster way to do this
> Regards soren
> 
> SampelReplace[data_List:{0, 1}, n_:1] :=
>   Module[{}, data[[Table[Random[Integer, {1, Length@data} ], {n}]]]]
> 
> SampelNoReplace[data_List, n_] := Module[{idx, len, res, d, hi, i},
>     d = data;
>     res = {};
>     len = hi = Length@d;
> 
>     For[i = 1, i <= n && i <= len, i++,
>       idx = Random[Integer, {1, hi--} ];
>       AppendTo[res, d[[idx]]];
>       d = Drop[d, {idx}];
>       ];
>     res
>     ]


This comes up from time to time. Have a look at

http://forums.wolfram.com/mathgroup/archive/2001/Jan/msg00087.html

or

http://forums.wolfram.com/mathgroup/archive/2001/Apr/msg00263.html

Daniel Lichtblau
Wolfram Research


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