digitsBase {GLDEX}

Digit/Bit Representation of Integers in any Base

Description

Integer number representations in other Bases.

Formally, for every element N =x[i], compute the (vector of) “digits” A of the base b representation of the number N, N = \sum_{k=0}^M A_{M-k} b ^ k.
Revert such a representation to integers.

Usage

digitsBase(x, base = 2, ndigits = 1 + floor(log(max(x), base)))

Arguments

x

For digitsBase(): non-negative integer (vector) whose base base digits are wanted.

For as.intBase():
a list of numeric vectors, a character vector, or an integer matrix as returned by digitsBase(), representing digits in base base.

base

integer, at least 2 specifying the base for representation.

ndigits

number of bits/digits to use.

Value

For digitsBase(), an object, say m, of class "basedInt" which is basically a (ndigits x n) matrix where m[,i] corresponds to x[i], n <- length(x) and attr(m,"base") is the input base.

as.intBase() and the as.integer method for basedInt objects return an integer vector.

Note

digits and digits.v are now deprecated and will be removed from the sfsmisc package.

Author(s)

Martin Maechler, Dec 4, 1991 (for S-plus; then called digits.v).

Examples

digitsBase(0:12, 8) #-- octal representation

## This may be handy for just one number (and default decimal):
digits <- function(n, base = 10) as.vector(digitsBase(n, base = base))
digits(128, base = 8) # 2 0 0

## one way of pretty printing (base <= 10!)
b2ch <- function(db)
        noquote(gsub("^0+(.{1,})$"," \1", apply(db, 2, paste, collapse = "")))
b2ch(digitsBase(0:33, 2))  #->  0 1 10 11 100 101 ... 100001
b2ch(digitsBase(0:33, 4))  #->  0 1 2 3 10 11 12 13 20 ... 200 201

## Hexadecimal:
i <- c(1:20, 100:106)
M <- digitsBase(i, 16)
hexdig <- c(0:9, LETTERS[1:6])
cM <- hexdig[1 + M]; dim(cM) <- dim(M)
b2ch(cM) #->  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F 10 11 ... 6A