Class "abIndex" of Abstract Index Vectors

The "abIndex" class, short for “Abstract Index Vector”, is used for dealing with large index vectors more efficiently, than using integer (or numeric) vectors of the kind 2:1000000 or c(0:1e5, 1000:1e6).

Note that the current implementation details are subject to change, and if you consider working with these classes, please contact the package maintainers (packageDescription("Matrix")$Maintainer).

Objects from the Class

Objects can be created by calls of the form new("abIndex", ...), but more easily and typically either by as(x, "abIndex") where x is an integer (valued) vector, or directly by abIseq() and combination c(...) of such.

Slots

kind:

a character string, one of ("int32", "double", "rleDiff"), denoting the internal structure of the abIndex object.

x:

Object of class "numLike"; is used (i.e., not of length 0) only iff the object is not compressed, i.e., currently exactly when kind != "rleDiff".

rleD:

object of class "rleDiff", used for compression via rle.

Methods

as.numeric, as.integer, as.vector

signature(x = "abIndex"): ...

[

signature(x = "abIndex", i = "index", j = "ANY", drop = "ANY"): ...

coerce

signature(from = "numeric", to = "abIndex"): ...

coerce

signature(from = "abIndex", to = "numeric"): ...

coerce

signature(from = "abIndex", to = "integer"): ...

length

signature(x = "abIndex"): ...

Ops

signature(e1 = "numeric", e2 = "abIndex"): These and the following arithmetic and logic operations are not yet implemented; see Ops for a list of these (S4) group methods.

Ops

signature(e1 = "abIndex", e2 = "abIndex"): ...

Ops

signature(e1 = "abIndex", e2 = "numeric"): ...

Summary

signature(x = "abIndex"): ...

show

("abIndex"): simple show method, building on show(<rleDiff>).

is.na

("abIndex"): works analogously to regular vectors.

is.finite, is.infinite

("abIndex"): ditto.

Note

This is currently experimental and not yet used for our own code. Please contact us (packageDescription("Matrix")$Maintainer), if you plan to make use of this class.

Partly builds on ideas and code from Jens Oehlschlaegel, as implemented (around 2008, in the GPL'ed part of) package ff.

See also

rle (base) which is used here; numeric

Examples

showClass("abIndex")
#> Class "abIndex" [package "Matrix"]
#> 
#> Slots:
#>                                     
#> Name:       kind         x      rleD
#> Class: character   numeric   rleDiff
ii <- c(-3:40, 20:70)
str(ai <- as(ii, "abIndex"))# note
#> Formal class 'abIndex' [package "Matrix"] with 3 slots
#>   ..@ kind: chr "rleDiff"
#>   ..@ x   : int(0) 
#>   ..@ rleD:Formal class 'rleDiff' [package "Matrix"] with 2 slots
#>   .. .. ..@ first: int -3
#>   .. .. ..@ rle  :List of 2
#>   .. .. .. ..$ lengths: int [1:3] 43 1 50
#>   .. .. .. ..$ values : int [1:3] 1 -20 1
#>   .. .. .. ..- attr(*, "class")= chr "rle"
ai # -> show() method
#> Abstract Index vector (class 'abIndex') of length 95, kind "rleDiff"
#>  and slot "rleD":
#>  RLE difference (class 'rleDiff'): first = -3, "rle":
#>    Run Length Encoding
#>      lengths: int [1:3] 43 1 50
#>      values : int [1:3] 1 -20 1


stopifnot(identical(-3:20,
                    as(abIseq1(-3,20), "vector")))