Assigning the number of rows or columns

Function nrow<- assigns dim with a new number of rows.
Function ncol<- assigns dim with a new number of columns.

nrow(x) <- value
ncol(x) <- value

Arguments

x

a object that has dim AND can be assigned ONE new dimension

value

the new size of the assigned dimension

Details

Currently only asssigning new rows to ffdf is supported. The new ffdf rows are not initialized (usually become zero). NOTE that

Value

The object with a modified dimension

Author

Jens Oehlschlägel

See also

ffdf, dim.ffdf

Examples

  a <- as.ff(1:26)
  b <- as.ff(factor(letters)) # vmode="integer"
  c <- as.ff(factor(letters), vmode="ubyte")
  df <- ffdf(a,b,c)
  nrow(df) <- 2*26
  df
#> ffdf (all open) dim=c(52,3), dimorder=c(1,2) row.names=NULL
#> ffdf virtual mapping
#>   PhysicalName VirtualVmode PhysicalVmode  AsIs VirtualIsMatrix
#> a            a      integer       integer FALSE           FALSE
#> b            b      integer       integer FALSE           FALSE
#> c            c        ubyte         ubyte FALSE           FALSE
#>   PhysicalIsMatrix PhysicalElementNo PhysicalFirstCol PhysicalLastCol
#> a            FALSE                 1                1               1
#> b            FALSE                 2                1               1
#> c            FALSE                 3                1               1
#>   PhysicalIsOpen
#> a           TRUE
#> b           TRUE
#> c           TRUE
#> ffdf data
#>      a   b   c
#> 1  1   a   a  
#> 2  2   b   b  
#> 3  3   c   c  
#> 4  4   d   d  
#> 5  5   e   e  
#> 6  6   f   f  
#> 7  7   g   g  
#> 8  8   h   h  
#> :    :   :   :
#> 45 0   <0> a  
#> 46 0   <0> a  
#> 47 0   <0> a  
#> 48 0   <0> a  
#> 49 0   <0> a  
#> 50 0   <0> a  
#> 51 0   <0> a  
#> 52 0   <0> a  
  message("NOTE that the new rows have silently the first level 'a' for UNSIGNED vmodes")
#> NOTE that the new rows have silently the first level 'a' for UNSIGNED vmodes
  message("NOTE that the new rows have an illegal factor level <0> for SIGNED vmodes")
#> NOTE that the new rows have an illegal factor level <0> for SIGNED vmodes
  message("It is your responsibility to put meaningful content here")
#> It is your responsibility to put meaningful content here
  message("As an example we replace the illegal zeros by NA")
#> As an example we replace the illegal zeros by NA
  df$b[27:52] <- NA
  df
#> ffdf (all open) dim=c(52,3), dimorder=c(1,2) row.names=NULL
#> ffdf virtual mapping
#>   PhysicalName VirtualVmode PhysicalVmode  AsIs VirtualIsMatrix
#> a            a      integer       integer FALSE           FALSE
#> b            b      integer       integer FALSE           FALSE
#> c            c        ubyte         ubyte FALSE           FALSE
#>   PhysicalIsMatrix PhysicalElementNo PhysicalFirstCol PhysicalLastCol
#> a            FALSE                 1                1               1
#> b            FALSE                 3                1               1
#> c            FALSE                 2                1               1
#>   PhysicalIsOpen
#> a           TRUE
#> b           TRUE
#> c           TRUE
#> ffdf data
#>     a  b  c
#> 1  1  a  a 
#> 2  2  b  b 
#> 3  3  c  c 
#> 4  4  d  d 
#> 5  5  e  e 
#> 6  6  f  f 
#> 7  7  g  g 
#> 8  8  h  h 
#> :   :  :  :
#> 45 0  NA a 
#> 46 0  NA a 
#> 47 0  NA a 
#> 48 0  NA a 
#> 49 0  NA a 
#> 50 0  NA a 
#> 51 0  NA a 
#> 52 0  NA a 

  rm(a,b,c,df); gc()
#>           used (Mb) gc trigger  (Mb) max used  (Mb)
#> Ncells 1162483 62.1    1994352 106.6  1994352 106.6
#> Vcells 2166824 16.6    8790397  67.1  8790397  67.1