Factor codings

Function ram2ffcode creates the internal factor codes used by ff to store factor levels. Function ram2ramcode is a compatibility function used instead if RETURN_FF==FALSE.

ram2ffcode(value, levels, vmode)
ram2ramcode(value, levels)

Arguments

value

factor or character vector of values

levels

character vector of factor levels

vmode

one of the integer vmodes in .rammode

Details

Factors stored in unsigned vmodes .vunsigned have their first level represented as 0L instead of 1L.

Value

A vector of integer values representing the correspnding factor levels.

Author

Jens Oehlschlägel

See also

factor, levels.ff, vmode

Examples

 ram2ffcode(letters, letters, vmode="byte")
#>  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
#> [26] 26
 ram2ffcode(letters, letters, vmode="ubyte")
#>  [1]  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
#> [26] 25
 ram2ffcode(letters, letters, vmode="nibble")
#>  [1]  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
#> [26] 25
 message('note that ram2ffcode() does NOT warn that vmode="nibble" cannot store 26 levels')
#> note that ram2ffcode() does NOT warn that vmode="nibble" cannot store 26 levels