Can someone help me understand the following behavior of "[<-" ?
If I define a simple class based on a matrix, the [<- operation only
inserts into the first column:
> x <- matrix(rnorm(10),nrow=5,ncol=2)
> class(x) <- "foo"
> "[<-.foo" <- function(x, i, j, value) {
+ if(missing(i)) i <- 1:nrow(x)
+ if(missing(j)) j <- 1:ncol(x)
+
+ x <- unclass(x)
+ x <- NextMethod(.Generic)
+ class(x) <- "foo"
+ x
+ }
>
> x[] <- 100.0
> x
[,1] [,2]
[1,] 100 -0.1465296
[2,] 100 -0.2615796
[3,] 100 -0.8882629
[4,] 100 -0.2886357
[5,] 100 -0.9565273
attr(,"class")
[1] "foo"
Based on the behavior of [<- for a matrix, I would have thought that the
data for the whole object would be replaced.
for instance:
> y <- matrix(rnorm(10),nrow=5,ncol=2)
> y
[,1] [,2]
[1,] -0.55297049 -1.1896488
[2,] 0.06157438 -0.6628254
[3,] -0.28184208 -2.5260177
[4,] 0.61204398 -0.3492488
[5,] 0.43971216 1.8990789
> y[] <- 100
> y
[,1] [,2]
[1,] 100 100
[2,] 100 100
[3,] 100 100
[4,] 100 100
[5,] 100 100
>
Thanks,
Whit
code for above:
x <- matrix(rnorm(10),nrow=5,ncol=2)
x
class(x) <- "foo"
"[<-.foo" <- function(x, i, j, value) {
if(missing(i)) i <- 1:nrow(x)
if(missing(j)) j <- 1:ncol(x)
x <- unclass(x)
x <- NextMethod(.Generic)
class(x) <- "foo"
x
}
x[] <- 100.0
x
> R.Version()
$platform
[1] "i686-pc-linux-gnu"
$arch
[1] "i686"
$os
[1] "linux-gnu"
$system
[1] "i686, linux-gnu"
$status
[1] ""
$major
[1] "2"
$minor
[1] "3.1"
$year
[1] "2006"
$month
[1] "06"
$day
[1] "01"
$`svn rev`
[1] "38247"
$language
[1] "R"
$version.string
[1] "Version 2.3.1 (2006-06-01)"
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