       Re: Slow performance gathering property data from fitted

• To: mathgroup at smc.vnet.net
• Subject: [mg101033] Re: [mg101013] Slow performance gathering property data from fitted
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Sun, 21 Jun 2009 07:07:33 -0400 (EDT)

```
Don't use Table

data = {{0, 1}, {1, 0}, {3, 2}, {5, 4}};

lm = LinearModelFit[data, x, x];

piedlrmodels = Table[lm, {10000}];

(piedlrRsquared =
Table[piedlrmodels[[i]]["RSquared"], {i, 1,
Length[piedlrmodels]}]); // Timing

{15.5082,Null}

(piedlrRsquared2 = (#["RSquared"] & /@ piedlrmodels)); // Timing

{6.09562,Null}

piedlrRsquared == piedlrRsquared2

True

(%%/%%%)[]

0.393057

Bob Hanlon

---- 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

```

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