ff: ram2ffcode – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

ram2ffcode

Factor codings

Description

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.

Usage

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(s)

Jens Oehlschlägel

Examples

ram2ffcode(letters, letters, vmode="byte")
 ram2ffcode(letters, letters, vmode="ubyte")
 ram2ffcode(letters, letters, vmode="nibble")
 message('note that ram2ffcode() does NOT warn that vmode="nibble" cannot store 26 levels')

ff

Memory-Efficient Storage of Large Data on Disk and Fast Access Functions

v4.0.4

GPL-2 | GPL-3 | file LICENSE

Authors

Daniel Adler [aut], Christian Gläser [aut], Oleg Nenadic [aut], Jens Oehlschlägel [aut, cre], Martijn Schuemie [aut], Walter Zucchini [aut]

Initial release

2020-10-13