Extraction and replacement methods for class "disord"
extract.RdThe disord class provides basic arithmetic and extract/replace
methods for disord objects.
Class index is taken from the excellent Matrix package
and is a setClassUnion() of classes numeric,
logical, and character.
Methods
- [
signature(x = "disord", i = "ANY", j = "ANY"): ...- [
signature(x = "disord", i = "index", j = "index"): ...- [
signature(x = "disord", i = "index", j = "missing"): ...- [
signature(x = "disord", i = "missing", j = "index"): ...- [
signature(x = "disord", i = "missing", j = "missing"): ...- [
signature(x = "disord", i = "matrix", j = "missing"): ...- [<-
signature(x = "disord", i = "index", j = "index"): ...- [<-
signature(x = "disord", i = "index", j = "missing"): ...- [<-
signature(x = "disord", i = "missing", j = "index"): ...- [<-
signature(x = "disord", i = "matrix", j = "missing"): ...- [<-
signature(x = "disord", i = "missing", j = "missing"): ...- [[
signature(x = "disord", i = "index"): ...- [[<-
signature(x = "disord", i = "index",value="ANY"): ...- [
signature(x="disord",i="disindex",j="missing",drop="ANY"): ...- [
signature(x="disord",i="disindex",j="ANY",drop="ANY"): ...- [
signature(x="ANY",i="disindex",j="ANY",drop="ANY"): ...- [
signature(x="disord",i="disindex",j="missing",value="ANY"): ...- [
signature(x="disord",i="disindex",j="ANY",value="ANY"): ...- [<-
signature(x="disord",i="disindex",j="missing",drop="ANY"): ...- [[
signature("disord",i="disindex"): ...- [[
signature("ANY",i="disindex"): ...- [[<-
signature(x="disord",i="disindex",j="missing",value="ANY")...- [[<-
signature(x="ANY",i="disindex",j="ANY",value="ANY")...
The extraction method takes a drop argument which if
TRUE, returns the drop() of its value. Extraction, as
in x[i], is rarely useful. It is only defined if one extracts
either all, or none, of the elements: anything else is undefined.
Note that the hash code is unchanged if all elements are extracted
(because the order might have changed) but unchanged if none are
(because there is only one way to extract no elements).
Missing arguments for extraction and replacement are slightly
idiosyncratic. Extraction idiom such as x[] returns an object
identical to x except for the hash code, which is changed. I
can't quite see a sensible use-case for this, but the method allows
one to define an object y <- x[] for which x and
y are incompatible. Replacement idiom x[] <- v always
coerces to a vector.
Double square extraction, as in x[[i]] and x[[i]] <-
value, is via (experimental) disindex functionality.
Note
Package versions prior to disordR_0.0-9-6 allowed idiom such as
a <- disord(1:9)
a[a<3] + a[a>7]
but this is now disallowed. The issue is discussed in
inst/note_on_extraction.Rmd.
Examples
a <- disord(sample(9))
a
#> A disord object with hash 43963c8a6eee36862e8a4aaf50f1ba0306d37450 and elements
#> [1] 6 9 5 3 4 1 7 8 2
#> (in some order)
a + 6*a^2
#> A disord object with hash 43963c8a6eee36862e8a4aaf50f1ba0306d37450 and elements
#> [1] 222 495 155 57 100 7 301 392 26
#> (in some order)
a[a>5] # "give me all elements of a that exceed 5"
#> A disord object with hash 412ac542720e050a1f15362c9c5d90f644ad6ba9 and elements
#> [1] 6 9 7 8
#> (in some order)
a[] # a disord object, same elements as 'a', but with a different hash
#> A disord object with hash 5e5b63c3429f8742a954e30973ba5bd04bf8aed0 and elements
#> [1] 6 9 5 3 4 1 7 8 2
#> (in some order)
a[a<5] <- a[a<5] + 100 # "replace all elements of 'a' less than 5 with their value plus 100"
a
#> A disord object with hash 43963c8a6eee36862e8a4aaf50f1ba0306d37450 and elements
#> [1] 6 9 5 103 104 101 7 8 102
#> (in some order)
## Following expressions would return an error if executed:
if(FALSE){
a[1]
a[1] <- 44
a[1:2] <- a[3:4]
}
b <- disord(sample(9))
## Following expressions would also return an error if executed:
if(FALSE){
a+b # (not really an example of extraction)
a[b>5]
a[b>5] <- 100
a[b>5] <- a[b>5] + 44
}