The compatibility (makes knitr faster) obviously it's running sweave under the hood but:
- (IMPORTANT) the internal compatibility with Sweave has been dropped
as scheduled in the last version, and the **knitr** parser was greatly
simplified accordingly; Sweave users can call the function `Sweave2knitr()`
to convert old Rnw files to **knitr** files before running `knit()`
I wouldn't say that this is knitr integrating more deeply with R. This is just R finally allowing different engines to process vignettes than just Sweave - so really it's just that R isn't going to be as tightly integrated with Sweave.
o chooseCRANmirror() and chooseBioCmirror() gain an ind argument
o mcparallel has a new argument mc.interactive which can modify the
interactive flag in the child process. The new default is FALSE
which makes child processes non-interactive by default (this
prevents lock-ups due to children waiting for interactive input).
o scan() now warns when end-of-file occurs within a quoted string.
o count.fields() is now consistent with scan() in its handling of
newlines in quoted strings. Instead of triggering an error, this
results in the current line receiving NA as the field count, with
the next line getting the total count of the two lines.
o The default method of image() will plot axes of the class of xlim
and ylim (and hence of x and y if there is a suitable range()
method). Based on a suggestion of Michael Sumner.
o load() now has a verbose argument for debugging support, to print
the names of objects just before loading them.
o When loading a serialized object encounters a reference to a
namespace which cannot be loaded, this is replaced by a reference
to the global environment, with a warning.
o pairs() gains a line.main option for title placement.
o The remaining instances in which serialization to a raw vector
was limited to 2GB have been unlimited on a 64-bit platform, and
in most cases serialization to a vector of more than 1GB will be
o R CMD config now make use of personal Makevars files under ~/.R
and a site file Makevars.site, in the same way as R CMD SHLIB and
R CMD INSTALL. This makes the utility more useful in package
On Windows finding the personal files may require the environment
variable HOME set.
The old behaviour can be obtained with the new options
--no-user-files and --no-site-files.
o Alternatives to the site and user customization files
Makevars.site and ~/.R/Makevars can be specified _via_ the
environment variables R_MAKEVARS_SITE and R_MAKEVARS_USER
respectively. These can be used to suppress the use of the
default files by setting an empty value (where possible) or a
o sys.source() did not report error locations when keep.source =
o as.POSIXct.numeric was coercing origin using the tz argument and
not "GMT" as documented (PR#14973).
o The active binding to assign fields in reference classes has been
cleaned up to reduce dependence on the class' package
environment, also fixing bug in initializing read-only fields
(inspired by a report from Hadley Wickham).
o str(d) no longer gives an error when names(d) contain illegal
multibyte strings (PR#15247).