>>>>> Martin Maechler writes: > (RFC := Request For Comments)
My preference would be that we start by adding a version of sscanf(). -k >>>>> "Tim" == Tim Keighley <[EMAIL PROTECTED]> >>>>> on Thu, 23 Oct 2003 11:45:22 +1000 writes: Tim> Hi Martin, Tim> In October 2000 you wrote to r-help: >>>> which reminds me that I've had a desire for something like >>>> the old S function [from the blue book, and library(examples) I think] >>>> ichar(ch) >>>> which would return a vector of integers, each the (decimal) equivalent of >>>> the (ISO-latin1) representation of the corresponding characters in ch. >>>> >>>> This should be easy enough (and be done in C). >>>> Any volunteers? Tim> Did you get any volunteers? > no. > Thank you for reminding me! Tim> Is this function or an Tim> equivalent now available in R? I have been unsuccessful Tim> in my investigation but I do not have all the available Tim> CRAN packages, so it might be in one of them. > I've searched myself (we have almost all of them installed), and > didn't find anything. Tim> Cheers, Tim> Tim Keighley > I now did a first cut, using R only code, > (and realizing that most of chars8bit() should really happen in C). > I'm proposing to add something like this to R-devel in the near > future. > Note that AsciiToInt() and ichar() ar for S-plus and "old S" > compatibility, whereas I think we'd really want (equivalents) of > the three functions > digitsBase() > chars8bit() > strcodes() > in R eventually. > I'm very interested in feedback, > particularly > - function and arguments' naming > - proposals for improvements > - neat examples of usage. > Martin > Martin Maechler <[EMAIL PROTECTED]> http://stat.ethz.ch/~maechler/ > Seminar fuer Statistik, ETH-Zentrum LEO C16 Leonhardstr. 27 > ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND > phone: x-41-1-632-3408 fax: ...-1228 <>< > ### This was digits.v() in library(sfsmisc): > ### --> get it's help() file /u/maechler/R/Pkgs/sfsmisc/man/digits.Rd > digitsBase <- function(x, base = 2, ndigits = 1 + floor(log(max(x),base))) > { > ## Purpose: Give the vector A of the base-_base_ representation of _n_: > ## ------- n = sum_{k=0}^M A_{M-k} base ^ k , where M = length(a) - 1 > ## Value: MATRIX M where M[,i] corresponds to x[i] > ## c( result ) then contains the blocks in proper order .. > ## Author: Martin Maechler, Date: Wed Dec 4 14:10:27 1991 > ## ---------------------------------------------------------------- > ## Arguments: x: vector of non-negative integers > ## base: Base for representation > ## ndigits: Number of digits/bits to use > ## EXAMPLE: digitsBase(1:24, 8) #-- octal representation > ## ---------------------------------------------------------------- > if(any((x <- as.integer(x)) < 0)) > stop("`x' must be non-negative integers") > r <- matrix(0, nrow = ndigits, ncol = length(x)) > if(ndigits >= 1) for (i in ndigits:1) { > r[i,] <- x %% base > if (i > 1) x <- x %/% base > } > r > } > ### This is an improved version of make.ASCII() in 1991's ~/S/Good-string.S ! > chars8bit <- function(i = 0:255) > { > ## Purpose: Compute a character vector from its "ASCII" codes. > ## We seem to have to use this complicated way thru text and parse. > ## Author: Martin Maechler, Original date: Wed Dec 4, 1991 > ## ---------------------------------------------------------------- > i <- as.integer(i) > if(any(i < 0 | i > 255)) stop("`i' must be in 0:255") > i8 <- apply(digitsBase(i, base = 8), 2, paste, collapse="") > c8 <- paste('"\\', i8, '"', sep="") > eval(parse(text = paste("c(",paste(c8, collapse=","),")", sep=""))) > } > strcodes <- function(x, table = chars8bit(0:255)) > { > ## Purpose: R (code) implementation of old S's ichar() > ## ---------------------------------------------------------------------- > ## Arguments: x: character vector > ## ---------------------------------------------------------------------- > ## Author: Martin Maechler, Date: 23 Oct 2003, 12:42 > lapply(strsplit(x, ""), match, table = table) > } > ## S-PLUS has AsciiToInt() officially, and ichar() in library(examples): > AsciiToInt <- ichar <- function(strings) unname(unlist(strcodes(strings))) > ## Examples: > all8bit <- chars8bit(0:255) > matrix(all8bit, 32, 8, byrow = TRUE) > x <- c(a = "abc", bb = "BLA & blu", Person = "Mächler, Zürich") > strcodes(x) > AsciiToInt(x) > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-devel ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
