- CHANGES IN 4.0.0:
SIGNIFICANT USER-VISIBLE CHANGES:
* Packages need to be (re-)installed under this version (4.0.0) of
R.
* matrix objects now also inherit from class "array", so e.g.,
class(diag(1)) is c("matrix", "array"). This invalidates code
incorrectly assuming that class(matrix_obj)) has length one.
S3 methods for class "array" are now dispatched for matrix
objects.
* There is a new syntax for specifying _raw_ character constants
similar to the one used in C++: r"(...)" with ... any character
sequence not containing the sequence )". This makes it easier to
write strings that contain backslashes or both single and double
quotes. For more details see ?Quotes.
* R now uses a stringsAsFactors = FALSE default, and hence by
default no longer converts strings to factors in calls to
data.frame() and read.table().
A large number of packages relied on the previous behaviour and
so have needed/will need updating.
* The plot() S3 generic function is now in package base rather than
package graphics, as it is reasonable to have methods that do not
use the graphics package. The generic is currently re-exported
from the graphics namespace to allow packages importing it from
there to continue working, but this may change in future.
Packages which define S4 generics for plot() should be
re-installed and package code using such generics from other
packages needs to ensure that they are imported rather than rely
on their being looked for on the search path (as in a namespace,
the base namespace has precedence over the search path).
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