Getting and setting dimnames of ffdf

Getting and setting dimnames, columnnames or rownames

# S3 method for class 'ffdf'
dimnames(x)
  # S3 method for class 'ffdf'
dimnames(x) <- value
  # S3 method for class 'ffdf'
names(x)
  # S3 method for class 'ffdf'
names(x) <- value
  # S3 method for class 'ffdf'
row.names(x)
  # S3 method for class 'ffdf'
row.names(x) <- value

Arguments

x

a ffdf object

value

a character vector, or, for dimnames a list with two character vectors

Details

It is recommended not to assign row.names to a large ffdf object.

Value

The assignment function return the changed ffdf object. The other functions return the expected.

Author

Jens Oehlschlägel

See also

ffdf, dimnames.ff, rownames, colnames

Examples

  ffd <- as.ffdf(data.frame(a=1:26, b=letters, stringsAsFactors = TRUE))
  dimnames(ffd)
#> [[1]]
#> NULL
#> 
#> [[2]]
#> [1] "a" "b"
#> 
  row.names(ffd) <- letters
  dimnames(ffd)
#> [[1]]
#>  [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s"
#> [20] "t" "u" "v" "w" "x" "y" "z"
#> 
#> [[2]]
#> [1] "a" "b"
#> 
  ffd
#> ffdf (all open) dim=c(26,2), dimorder=c(1,2) row.names=character 
#> ffdf virtual mapping
#>   PhysicalName VirtualVmode PhysicalVmode  AsIs VirtualIsMatrix
#> a            a      integer       integer FALSE           FALSE
#> b            b      integer       integer FALSE           FALSE
#>   PhysicalIsMatrix PhysicalElementNo PhysicalFirstCol PhysicalLastCol
#> a            FALSE                 1                1               1
#> b            FALSE                 2                1               1
#>   PhysicalIsOpen
#> a           TRUE
#> b           TRUE
#> ffdf data
#>    a  b
#> a  1 a 
#> b  2 b 
#> c  3 c 
#> d  4 d 
#> e  5 e 
#> f  6 f 
#> g  7 g 
#> h  8 h 
#> :  :  :
#> s 19 s 
#> t 20 t 
#> u 21 u 
#> v 22 v 
#> w 23 w 
#> x 24 x 
#> y 25 y 
#> z 26 z 
  rm(ffd); gc()
#>           used (Mb) gc trigger  (Mb) max used  (Mb)
#> Ncells 1136619 60.8    1994352 106.6  1994352 106.6
#> Vcells 2107791 16.1    8388608  64.0  3981144  30.4