Re: [R] R is GNU S, not C.... [was "how to get or store ....."]

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Thu 08 Dec 2005 - 03:34:00 EST

On 12/7/05, Dave Roberts <droberts@montana.edu> wrote:
> Well, this has been an interesting thread. I guess my own perspective
> is warped, having never been a C programmer. My native languages are
> FORTRAN, python, and R, all of which accept (or demand) a linefeed as a
> terminator, rather than a semicolon, and two of which are very
> particular about whitespace.
>
> Accepting for a moment Ted's argument about wanting to compact his code,
> the problem as I understand it is that ";" is a statement separator, not
> a statement terminator, so that Ted really does need all those ";" in
> between his statements on a single line, but that the last one implies a
> NULL statement on every line. Given that the ";" facilitates compacting
> lines in vi (or vim), how about when the code is compacted you try
>
> 1,$s/;$//
>
> which will remove all the final trailing ";" leaving the other necessary
> ";" separators.

But watch out for this:

x <- "abc;
def"

>
> Dave R.
>
> (Ted Harding) wrote:
> > On 06-Dec-05 Martin Maechler wrote:
> >
> >>[But really, I'm more concerned and quite bit disappointed by
> >> the diehard ";" lovers]
> >>
> >>Martin Maechler
> >
> >
> > Well, while not die-hard, I will put in my own little reason
> > for often using ";" at the end of lines which don't need them.
> >
> > Basically, this is done to protect me from myself (so in fact
> > is quite a strong reason).
> >
> > I tend to develop extended R code in a "side-window", using
> > a text editor (vim) in that window, and cut&pasting the
> > chunks of R code from that window into the R window.
> > This usually means that I have a lot of short lines,
> > since it is easier when developing code to work with the
> > commands one per line, as they are easier to find and
> > less likely to be "corrected" erroneously.
> >
> > Finally, when when I am content that the code does the job
> > I then put several short lines into one longer one.
> >
> > For example (a function to do with sampling with probability
> > proportional to weights); first, as written line-by-line:
> >
> > myfunction <- function(X,n1,n2,n3,WTS){
> > N1<-n1;
> > N2<-n1+n2;
> > N3<-n1+n2+n3;
> > # first selection
> > pii<-WTS/sum(WTS);
> > alpha<-N2;
> > Pi<-alpha*pii;
> > r<-runif(N3);
> > ix<-sort(which(r<=Pi));
> > # second selection
> > ix0<-(1:N3);
> > ix3<-ix0[-ix];
> > ix20<-ix0[ix];
> > W<-WTS[ix];
> > pii<-W/sum(W);
> > Pi<-N1*pii;
> > r<-runif(length(Pi));
> > ix10<-sort(which(r<=Pi));
> > ix1<-ix20[ix10];
> > ix2<-ix20[-ix10];
> > # return the results
> > list(X1=X[ix1],X2=X[ix2],X3=X[ix3],ix1=ix1,ix2=ix2,ix3=ix3)
> > }
> >
> >
> > Having got that function right, with 'vim' in command mode
> > successive lines are readily brought up to the current line
> > by simply pressing "J", which is very fast. This, in the
> > above case, then results in
> >
> > MARselect<-function(X,n1,n2,n3,WTS){
> > N1<-n1; N2<-n1+n2; N3<-n1+n2+n3;
> > # first selection
> > pii<-WTS/sum(WTS); alpha<-N2; Pi<-alpha*pii;
> > r<-runif(N3); ix<-sort(which(r<=Pi));
> > # second selection
> > ix0<-(1:N3); ix3<-ix0[-ix]; ix20<-ix0[ix];
> > W<-WTS[ix]; pii<-W/sum(W); Pi<-N1*pii;
> > r<-runif(length(Pi)); ix10<-sort(which(r<=Pi));
> > ix1<-ix20[ix10]; ix2<-ix20[-ix10];
> > # return the results
> > list(X1=X[ix1],X2=X[ix2],X3=X[ix3],ix1=ix1,ix2=ix2,ix3=ix3)
> > }
> >
> > The greater readability of the first relative to the second is
> > obvious. The compactness of the second relative to the first
> > is evident. Obtaining the second from the first by repeated "J"
> > is very quick.
> >
> > BUT -- if I had not put the ";" at the ends of the lines in the
> > string-out version (which is easy to do as you type in the line
> > in the first place), then it would be much more trouble to get
> > the second version, and very easy to get it wrong!
> >
> > Also, being long used to programming in C and octave/matlab,
> > putting ";" at the end of a command is an easy reflex, and of
> > course does no harm at all to an R command.
> >
> > Not that I'm trying to encourage others to do the same as I
> > do -- as I said, it's a self-protective habit -- but equally
> > if people (e.g. me) may find it useful I don't think it should
> > be discouraged either -- especially on "aesthetic" grounds!
> >
> > Just my little bit ...
> >
> > Best wishes,
> > Ted.
> >
> >
> > --------------------------------------------------------------------
> > E-Mail: (Ted Harding) <Ted.Harding@nessie.mcc.ac.uk>
> > Fax-to-email: +44 (0)870 094 0861
> > Date: 06-Dec-05 Time: 19:02:23
> > ------------------------------ XFMail ------------------------------
> >
> > ______________________________________________
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> > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
> >
> >
>
>
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> David W. Roberts office 406-994-4548
> Professor and Head FAX 406-994-3190
> Department of Ecology email droberts@montana.edu
> Montana State University
> Bozeman, MT 59717-3460
>
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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 Received on Thu Dec 08 03:48:02 2005

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