From: Stephen Milborrow <milbo_at_sonic.net>

Date: Mon, 14 Mar 2011 10:46:34 +0200

Date: Thu, 27 Jan 2011 14:22:54 +0100

From: Rasti Matus <matus.rasti_at_gmail.com> To: r-help_at_r-project.org

Subject: [R] selection of hinge function with restrictions, machine learning, earth package,

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Mon 14 Mar 2011 - 08:55:36 GMT

Date: Mon, 14 Mar 2011 10:46:34 +0200

On 2011-01-27 14:22, Rasti Matus wrote:

> I have a few questions regarding machine learning packages in R,

*> e.g. earth package ...
**>
**> 1) How could I force the algorithm to generate knots only with
**> values < 90 for variable doy?
*

Not possible in the current implementation. In principle it would be possible to extend earth so the user-defined "allowed" function includes a knot parameter. But internally in earth's C code, the search for knots is highly optimized and any extra code in there to possibly call a user-defined function would slow down earth considerably.

> 2) Is it possible to restrict the algorithm to generate maximum

*> number of terms per a selected variable e.g. humidity? e.g. 1
**> term instead of 2?
*

Not possible in the current implementation. This would require modifying earth to include an extension to the backward pass to call a user-defined function (similar to "allowed"). That would be a lot of work.

Date: Thu, 27 Jan 2011 14:22:54 +0100

From: Rasti Matus <matus.rasti_at_gmail.com> To: r-help_at_r-project.org

Subject: [R] selection of hinge function with restrictions, machine learning, earth package,

Message-ID:

<AANLkTiku1a6qro7vf0a8A7cks-a=qrVS_nrRZy4_dP1B@mail.gmail.com> Content-Type: text/plain

Hi,

I have a few questions regarding machine learning packages in R, e.g.
earth package

and its forward pass and prunning pass, and hinge functions selection in the
example below.

- How could I force the algorithm to generate knots in hinge function only with values < 90 for e.g. variable doy?
- Is it possible to restrict the algorithm to generate maximum number of terms per a selected variable e.g. humidity? e.g. 1 term instead of 2?

Thanks a lot.

rasti

>library(faraway)

*>data(ozone)
**>a=earth(O3~.,data=ozone)
**>summary(a)
*

Call: earth(formula=O3~., data=ozone)

coefficients (Intercept) 8.6910756 h(vh-5740) 0.0152607 h(5740-vh) -0.0130076 h(9-wind) 0.3044601 h(humidity-41) 0.2753048 h(humidity-54) -0.2615068 h(temp-58) 0.3801961 h(ibh-1069) -0.0006189 h(1069-ibh) -0.0029057 h(dpg-11) -0.1060948 h(80-vis) 0.0459011 h(doy-89) 0.0471836 h(89-doy) -0.1264530 h(doy-159) -0.0915781

Selected 14 of 19 terms, and 8 of 9 predictors Importance: temp, ibh, doy, dpg, humidity, vh, vis, wind, ibt-unused Number of terms at each degree of interaction: 1 13 (additive model) GCV 14.85938 RSS 4134.014 GRSq 0.769177 RSq 0.8042181

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