Incrementing an ff or ram object

Yet another assignment interface in order to allow to formulate x[index,...,add=TRUE]<-value in a way which works transparently, not only for ff, but also for ram objects: add(x, value, index, ...).

Usage

add(x, ...)
# S3 method for class 'ff'
add(x, value, ...)
# Default S3 method
add(x, value, ...)

Arguments

x: an ff or ram object
value: the amount to increment, possibly recylcled
...: further arguments – especially index information – passed to [<- or [<-.ff

Value

invisible()

Author

Jens Oehlschlägel

Note

Note that add.default changes the object in its parent frame and thus violates R's usual functional programming logic. Duplicated index positions should be avoided, because ff and ram objects behave differently:


  add.ff(x, 1, c(3,3))
  # will increment x at position 3 TWICE by 1, while
  add.default(x, 1, c(3,3))
  # will increment x at position 3 just ONCE by 1

Examples

   message("incrementing parts of a vector")
#> incrementing parts of a vector
   x <- ff(0, length=12)
   y <- rep(0, 12)
   add(x, 1, 1:6)
   add(y, 1, 1:6)
   x
#> ff (open) double length=12 (12)
#>  [1]  [2]  [3]  [4]  [5]  [6]       [7]  [8]  [9] [10] [11] [12] 
#>    1    1    1    1    1    1    :    0    0    0    0    0    0 
   y
#>  [1] 1 1 1 1 1 1 0 0 0 0 0 0

   message("incrementing parts of a matrix")
#> incrementing parts of a matrix
   x <- ff(0, dim=3:4)
   y <- array(0, dim=3:4)
   add(x, 1, 1:2, 1:2)
   add(y, 1, 1:2, 1:2)
   x
#> ff (open) double length=12 (12) dim=c(3,4) dimorder=c(1,2)
#>      [,1] [,2] [,3] [,4]
#> [1,]    1    1    0    0
#> [2,]    1    1    0    0
#> [3,]    0    0    0    0
   y
#>      [,1] [,2] [,3] [,4]
#> [1,]    1    1    0    0
#> [2,]    1    1    0    0
#> [3,]    0    0    0    0

   message("BEWARE that ff and ram methods differ in treatment of duplicated index positions")
#> BEWARE that ff and ram methods differ in treatment of duplicated index positions
   add(x, 1, c(3,3))
   add(y, 1, c(3,3))
   x
#> ff (open) double length=12 (12) dim=c(3,4) dimorder=c(1,2)
#>      [,1] [,2] [,3] [,4]
#> [1,]    1    1    0    0
#> [2,]    1    1    0    0
#> [3,]    2    0    0    0
   y
#>      [,1] [,2] [,3] [,4]
#> [1,]    1    1    0    0
#> [2,]    1    1    0    0
#> [3,]    1    0    0    0

   rm(x); gc()
#>           used (Mb) gc trigger  (Mb) max used  (Mb)
#> Ncells 1110208 59.3    2239654 119.7  2239654 119.7
#> Vcells 2017046 15.4    8388608  64.0  5871749  44.8