ram2ffcode: Factor codings

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

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

See Also

factor, levels.ff, vmode

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 documentation built on Feb. 16, 2023, 7:48 p.m.