[R] Why does substr<- truncate and not replace...

[Prof Brian D Ripley]

On 8 Sep 2001, Peter Dalgaard BSA wrote:

> Thomas Vogels <tov at ece.cmu.edu> writes:
>
> > ... when the replacement string is shorter than the portion of the
> > string to be replaced?
> >
> > The documentation to substr (in R 1.3.1) gives me:
> >
> >      If the portion to be replaced is longer than the replacement
> >      string, then only the portion the length of the string is
> >      replaced.
> >
> > And so I try:
> >
> > R> x <- "abcdef"
> > R> substr(x,2,3) <- "xy" #ok
> > R> x
> > [1] "axydef"
> > R> substr(x,2,3) <- "w" #ko
> > R> x
> > [1] "aw"
> >
> > hmm, I would have expected "awdef".  Am I reading the docs wrong?  (Or
> > am I just blinded to expect this string because that's what Perl would do?)
> >
> > Thanks!
> >   -tom
>
> Looks like a bit of a bug. I bet the \0 terminator gets copied in from
> the replacement.

Yes, the test was one off. Fixed now.


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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