Digit/Bit Representation of Integers in any Base
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.
digitsBase(x, base = 2, ndigits = 1 + floor(log(max(x), base)))
x |
For For |
base |
integer, at least 2 specifying the base for representation. |
ndigits |
number of bits/digits to use. |
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.
digits and digits.v are now deprecated and will be
removed from the sfsmisc package.
Martin Maechler, Dec 4, 1991 (for S-plus; then called digits.v).
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 ... 6APlease choose more modern alternatives, such as Google Chrome or Mozilla Firefox.