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MathGroup Archive 2005

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Re: problems with memory usage

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63314] Re: problems with memory usage
  • From: Bill Rowe <readnewsciv at earthlink.net>
  • Date: Fri, 23 Dec 2005 05:08:37 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

On 12/20/05 at 11:35 PM, marcellesantos at yahoo.com (Marcelle Santos)
wrote:

>I have to fit a model to a long set of data from previous
>calculations. These data are in a file called "ptab.m", which has
>this structure:

>{k1,{{x1,y1},{x2,y2},{x3,y3},...}}
>{k2,{{x1,y1},{x2,y2},{x3,y3},...}}

The primary tool for fitting models to data is FindFit which handles both linear and non-linear models. FindFit wants to see the data list in the form of an nXm matrix. So, I assume what you need to do is transform the data structure into something FindFit accepts, i.e.,

In[17]:=
data = {{k1,{{x1, y1}, {x2, y2}, {x3, y3}}}, 
       {k2, {{x1, y1}, {x2, y2}, {x3, y3}}}}; 

In[18]:=
Join @@ Transpose /@ 
   (Join[{Table[First[#1], {Length[Last[#1]]}]}, 
         Transpose[Last[#1]]]&)/@ data
Out[18]=
{{k1, x1, y1}, {k1, x2, y2}, 
  {k1, x3, y3}, {k2, x1, y1}, 
  {k2, x2, y2}, {k2, x3, y3}}
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