[Rd] R for windows: Why is Rtools not part of the R-distribution

[Søren Højsgaard]

Dear all,

This issue may have come up before, but then I have overlooked it: I
wonder if there are good reasons that rtools is not a part of R for
windows? 

If, for example, in a teaching situation you want the students to fetch
a recent version of a package from e.g. github, then it would be easy
if one needed not go through the steps of installing the rtools outside
of R. There may of course also be alternatives that I am not aware of?

As I wrote, the must be good reasons - I just can't spot them (it can't
really be the size of distribution any longer).

Best regards
Søren
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Re: [Rd] subset argument in nls() and possibly other functions

[Balasubramanian Narasimhan]

For the example provided below, the subsetting happens in evaluating the 
call to stats::model.formula in line 583 of nls.R 
(https://github.com/wch/r-source/blob/e91be22f6f37644e5a0ba74a3dfe504a3a29e9f7/src/library/stats/R/nls.R#L583) 
returning an appropriate (subsetted) data frame.


-Naras

On 7/13/21 4:21 PM, J C Nash wrote:

In mentoring and participating in a Google Summer of Code project "Improvements to 
nls()",
I've not found examples of use of the "subset" argument in the call to nls(). 
Moreover,
in searching through the source code for the various functions related to 
nls(), I can't
seem to find where subset is used, but a simple example, included below, 
indicates it works.
Three approaches all seem to give the same results.

Can someone point to documentation or code so we can make sure we get our 
revised programs
to work properly? The aim is to make them more maintainable and provide 
maintainer documentation,
along with some improved functionality. We seem, for example, to already be 
able to offer
analytic derivatives where they are feasible, and should be able to add 
Marquardt-Levenberg
stabilization as an option.

Note that this "subset" does not seem to be the "subset()" function of R.

John Nash

# CroucherSubset.R -- https://walkingrandomly.com/?p=5254

xdata = c(-2,-1.64,-1.33,-0.7,0,0.45,1.2,1.64,2.32,2.9)
ydata = 
c(0.699369,0.700462,0.695354,1.03905,1.97389,2.41143,1.91091,0.919576,-0.730975,-1.42001)
Cform <- ydata ~ p1*cos(p2*xdata) + p2*sin(p1*xdata)
Cstart<-list(p1=1,p2=0.2)
Cdata<-data.frame(xdata, ydata)
Csubset<-1:8 # just first 8 points

# Original problem - no subset
fit0 = nls(ydata ~ p1*cos(p2*xdata) + p2*sin(p1*xdata), data=Cdata, 
start=list(p1=1,p2=.2))
summary(fit0)

# via subset argument
fit1 = nls(ydata ~ p1*cos(p2*xdata) + p2*sin(p1*xdata), data=Cdata, 
start=list(p1=1,p2=.2), subset=Csubset)
summary(fit1)

# via explicit subsetting
Csdata <- Cdata[Csubset, ]
Csdata
fit2 = nls(ydata ~ p1*cos(p2*xdata) + p2*sin(p1*xdata), data=Csdata, 
start=list(p1=1,p2=.2))
summary(fit2)

# via weights -- seems to give correct observation count if zeros not recognized
wts <- c(rep(1,8), rep(0,2))
fit3 = nls(ydata ~ p1*cos(p2*xdata) + p2*sin(p1*xdata), data=Cdata, 
weights=wts, start=list(p1=1,p2=.2))
summary(fit3)

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