R devel - Oct 2007 - dget not restoring dput in R 2.6.0 (PR#10350)

Full_Name: David States
Version: 2.6.0
OS: Windows XP64
Submission from: (NULL) (141.211.38.9)


# The pair of commands
#
# dput(object, "file.dput")
# object = dget("file.dput")
#
# should be a no op, but this is not working correctly for all objects.
#
# Simple example:
#
# make a simple object of class "hclust"
cl = hclust(dist(matrix(nrow=4,ncol=4, c(1:16))))
# save it to a file using dput
dput(cl, "cl.dput")
# the following two commands should give identical results, but they dont
str(cl)
str(dget("cl.dput"))
# plot also fails to interpret the labels on the restore object correctly
par(mfrow=c(2,1))
plot(cl)
plot(dget("cl.dput"))

On Wed, 17 Oct 2007, dstates at umich.edu wrote:
> Full_Name: David States
> Version: 2.6.0
> OS: Windows XP64
> Submission from: (NULL) (141.211.38.9)
>
>
> # The pair of commands
> #
> # dput(object, "file.dput")
> # object = dget("file.dput")
> #
> # should be a no op, but this is not working correctly for all objects.
Not so, and it says so on the help page:

      Deparsing an object is difficult, and not always possible.  With
      the default 'control', 'dput()' attempts to deparse in a
way that
      is readable, but for more complex or unusual objects, not likely
      to be parsed as identical to the original.  Use 'control =
"all"'
      for the most complete deparsing; use 'control = NULL' for the
      simplest deparsing, not even including attributes.

Had you followed the advice, your example would have worked.

dump() is more accurate than dput(), and save() more so than either.
> #
> # Simple example:
> #
> # make a simple object of class "hclust"
> cl = hclust(dist(matrix(nrow=4,ncol=4, c(1:16))))
> # save it to a file using dput
> dput(cl, "cl.dput")
> # the following two commands should give identical results, but they dont
> str(cl)
> str(dget("cl.dput"))
> # plot also fails to interpret the labels on the restore object correctly
> par(mfrow=c(2,1))
> plot(cl)
> plot(dget("cl.dput"))
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595