R-beta: S compatibility
Ross Ihaka
ihaka at stat.auckland.ac.nz
Fri Aug 14 23:39:29 CEST 1998
From r-help-owner at stat.math.ethz.ch Fri Aug 14 22:21 NZS 1998
From: Jim Lindsey <jlindsey at alpha.luc.ac.be>
Subject: R-beta: S compatibility
To: r-help at stat.math.ethz.ch (r-help)
Date: Fri, 14 Aug 1998 12:24:21 +0200 (MET DST)
Once again, I foolishly attempted a major port of S, ratfor, and
Fortran code (hidden Markov models from an article in the latest Can
Jr Stat) to R without access to S-Plus itself. Here are some problems
I found before abandoning:
1. replicating a factor does not give a factor:
is.factor(rep(gl(2,1,2),2)) is FALSE
I have just implemented this. It will show up in the development version
momentarily.
2. sample() does not have the option, prob=
This is a good little exercise for someone :-). Anyone want to write a
C function which does this. I.e. we want a function which takes a
vector of probabilities and returns the sampled values. We probably
want with and without replacement. Given such a function it would be
about two minutes work to integrate it into R.
3. glm()$assign does not exist
4. glm()$contrast is very different from S - apparently the latter is
a list with one member per variable instead of a copy of the options
in effect
5. C() does not exist (something to do with contrasts, which are
apparently handled much differently in S-Plus)
I have had the contrasts stuff on my todo list for a while. Expect
(more) compatibility soon.
6. dummy.coef() does not exist
7. something else I have now forgotten...
In general, almost all aspects of model fitting in the two seem
to be completely incompatible.
We try to be moderately clean-room. To get particular details right
we need a clear description of what is needed.
Ross
PS: Splus (= S Version 4) for Linux is imminent (At least Bell Labs
has delivered it to MathSoft). You might want to look into it.
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