| cbind2 {methods} | R Documentation |
Combine two matrix-like R objects by columns (cbind2)
or rows (rbind2). These are (S4) generic functions with default
methods.
cbind2(x, y, ...) rbind2(x, y, ...)
x |
any R object, typically matrix-like. |
y |
any R object, typically similar to |
... |
optional arguments for methods. |
The main use of cbind2 (rbind2) is to be called
recursively by cbind() (rbind()) when both of
these requirements are met:
There is at least one argument that is an S4 object, and
S3 dispatch fails (see the Dispatch section under cbind).
The methods on cbind2 and rbind2 effectively define the
type promotion policy when combining a heterogeneous set of
arguments. The homogeneous case, where all objects derive from some S4
class, can be handled via S4 dispatch on the ... argument via
an externally defined S4 cbind (rbind) generic.
Since (for legacy reasons) S3 dispatch is attempted first, it is
generally a good idea to additionally define an S3 method on
cbind (rbind) for the S4 class. The S3 method will be
invoked when the arguments include objects of the S4 class, along with
arguments of classes for which no S3 method exists. Also, in case there
is an argument that selects a different S3 method (like the one for
data.frame), this S3 method serves to introduce an ambiguity in
dispatch that triggers the recursive fallback to cbind2
(rbind2). Otherwise, the other S3 method would be called, which
may not be appropriate.
A matrix (or matrix like object) combining the columns (or rows) of
x and y. Note that methods must construct
colnames and rownames from the
corresponding column and row names of x and y (but not
from deparsing argument names such as in cbind(...,
deparse.level = d) for d >= 1).
signature(x = "ANY", y = "ANY")the default method using R's internal code.
signature(x = "ANY", y = "missing")the default method for one argument using R's internal code.
cbind, rbind;
further, cBind, rBind in
the Matrix package.
cbind2(1:3, 4)
m <- matrix(3:8, 2,3, dimnames=list(c("a","b"), LETTERS[1:3]))
cbind2(1:2, m) # keeps dimnames from m
## rbind() and cbind() now make use of rbind2()/cbind2() methods
setClass("Num", contains="numeric")
setMethod("cbind2", c("Num", "missing"),
function(x,y, ...) { cat("Num-miss--meth\n"); as.matrix(x)})
setMethod("cbind2", c("Num","ANY"), function(x,y, ...) {
cat("Num-A.--method\n") ; cbind(getDataPart(x), y, ...) })
setMethod("cbind2", c("ANY","Num"), function(x,y, ...) {
cat("A.-Num--method\n") ; cbind(x, getDataPart(y), ...) })
a <- new("Num", 1:3)
trace("cbind2")
cbind(a)
cbind(a, four=4, 7:9)# calling cbind2() twice
cbind(m,a, ch=c("D","E"), a*3)
cbind(1,a, m) # ok with a warning
untrace("cbind2")