Re: Slow performance gathering property data from fitted

• To: mathgroup at smc.vnet.net
• Subject: [mg101022] Re: [mg101013] Slow performance gathering property data from fitted
• From: DrMajorBob <btreat1 at austin.rr.com>
• Date: Sun, 21 Jun 2009 07:05:22 -0400 (EDT)
• References: <200906200803.EAA16775@smc.vnet.net>
• Reply-to: drmajorbob at bigfoot.com

```Did you do something equivalent to this?

data := Table[{3 + i + RandomReal[{-3, 7}],
i + RandomReal[{-2, 5}]}, {i, 1, 20}]

Timing[models = Array[LinearModelFit[data, x, x] &, 70000];]

{90.2283, Null}

Timing[rsquares = Through[models@"RSquared"];]

{40.3059, Null}

ListPlot@rsquares

Notice, the RSquare values came out faster than the model fitting.

Bobby

On Sat, 20 Jun 2009 03:03:15 -0500, Todd Allen <genesplicer28 at yahoo.com>
wrote:

>
> Hi All,
>
>    During some recent research I asked Mathematica to calculate 70,000
> simple linear regression fits to 70,000 small datasets.  This worked
> well and resulted in a list of 70,000 fitted model objects being
> finished in under 5 minutes.
>
>   My next step was to collect the RSquared property for each of the
> 70,000 fits contained in the list, and Mathematica took over 3 hours to
> accomplish this.  This seems horrendously slow simply to gather values
> from a list.  Has anyone ran into a similar problem?  Any suggestions
> how I might be able to significantly speed the gathering of properties
> from large lists of fitted model objects?
>
>
>   The snippet of code I was using to gather the RSquared values is below:
>
> piedlrRsquared =
>   Table[piedlrmodels[[i]]["RSquared"], {i, 1, Length[piedlrmodels]}] //
>     Timing;
>
>
>    Thanks for any advice you might have!
>
> Todd
>
>
>

--
DrMajorBob at bigfoot.com

```

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