Hi all
If I have a string, say "ABCDA", and I want to convert this to the sum
of the letter values, e.g.
A -> 1
B -> 2
etc, so "ABCDA" = 1+2+3+4+1 = 11
Is there an elegant way to do this? Trying something like
which(LETTERS %in% unlist(strsplit("ABCDA", "")))
is not quite correct, as it does not count repeated characters. I guess what I
need is some kind of lookup table?
Cheers
Rory
Rory Winston
RBS Global Banking & Markets
280 Bishopsgate, London, EC2M 4RB
Office: +44 20 7085 4476
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on 11/24/2008 08:57 AM Rory.WINSTON at rbs.com wrote:> Hi all > > If I have a string, say "ABCDA", and I want to convert this to the sum of the letter values, e.g. > > A -> 1 > B -> 2 > > etc, so "ABCDA" = 1+2+3+4+1 = 11 > > Is there an elegant way to do this? Trying something like > > which(LETTERS %in% unlist(strsplit("ABCDA", ""))) > is not quite correct, as it does not count repeated characters. I guess what I need is some kind of lookup table? > > Cheers > Rory> sum(as.numeric(factor(unlist(strsplit("ABCDA", "")))))[1] 11 Convert the letters to factors, after splitting the vector, which then enables the use of the underlying numeric codes:> as.numeric(factor(unlist(strsplit("ABCDA", ""))))[1] 1 2 3 4 1 HTH, Marc Schwartz
Here are a couple of solutions. The first matches each character against LETTERS returning the position number in LETTERS of the match. strsplit returns a list of which we want the first element and then we sum that. The second applies function(x) match(x, LETTERS), which is specified in formula notation, to each letter and simplifies the result using sum. sum(match(strsplit(s, "")[[1]], LETTERS)) library(gsubfn) strapply(s, ".", ~ match(x, LETTERS), simplify = sum) On Mon, Nov 24, 2008 at 9:57 AM, <Rory.WINSTON at rbs.com> wrote:> Hi all > > If I have a string, say "ABCDA", and I want to convert this to the sum of the letter values, e.g. > > A -> 1 > B -> 2 > > etc, so "ABCDA" = 1+2+3+4+1 = 11 > > Is there an elegant way to do this? Trying something like > > which(LETTERS %in% unlist(strsplit("ABCDA", ""))) > is not quite correct, as it does not count repeated characters. I guess what I need is some kind of lookup table? > > Cheers > Rory > > Rory Winston > RBS Global Banking & Markets > 280 Bishopsgate, London, EC2M 4RB > Office: +44 20 7085 4476 > > > > *********************************************************************************** > The Royal Bank of Scotland plc. Registered in Scotland No 90312. Registered Office: 36 St Andrew Square, Edinburgh EH2 2YB. > Authorised and regulated by the Financial Services Authority > > This e-mail message is confidential and for use by the=2...{{dropped:25}} > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >
G'day Rory, On Mon, 24 Nov 2008 14:57:57 +0000 <Rory.WINSTON at rbs.com> wrote:> If I have a string, say "ABCDA", and I want to convert this to the > sum of the letter values, e.g. > > A -> 1 > B -> 2 > > etc, so "ABCDA" = 1+2+3+4+1 = 11 > > Is there an elegant way to do this? [...]R> sum(as.numeric(factor(unlist(strsplit("ABCDA","")), levels=LETTERS))) [1] 11 R> sum(as.numeric(factor(unlist(strsplit("ABCEA","")), levels=LETTERS))) [1] 12 HTH. Best wishes, Berwin =========================== Full address ============================Berwin A Turlach Tel.: +65 6515 4416 (secr) Dept of Statistics and Applied Probability +65 6515 6650 (self) Faculty of Science FAX : +65 6872 3919 National University of Singapore 6 Science Drive 2, Blk S16, Level 7 e-mail: statba at nus.edu.sg Singapore 117546 http://www.stat.nus.edu.sg/~statba
Rory Winston wrote:> I have got it to work in a fairly non-elegant manner, using thefollowing code:> > sum ( unlist(lapply(strsplit("TESTING",""), function(x)match(x,LETTERS) )) )> > And over a list of names, this becomes: > > lapply(namelist, function(Z) { sum ( unlist(lapply(strsplit(Z,""),function(x) match(x,LETTERS) )) ) } )> > But this is kind of ugly.... > > Rory Winston > RBS Global Banking & Markets > Office: +44 20 7085 4476Do you mean that the nested lapply's are kind of ugly. You don't need them. I think the following does the same as what you wrote f1 <- function(namelist)lapply(strsplit(namelist,""), function(x) sum(match(x,LETTERS))) where your code as a function would be f0 <- function(namelist)lapply(namelist, function(Z) { sum ( unlist(lapply(strsplit(Z,""), function(x) match(x,LETTERS) )) ) } ) (Since f0() and f1() return lists of scalar integers, it might make more sense to call unlist() on their outputs before returning them.) Another approach is to use a named vector of character values to map characters to values, such as in f2 <- function(namelist) { values <- c(seq_along(LETTERS), seq_along(letters), 0L, 0L, 0L) names(values) <- c(LETTERS, letters, " ", "-", ".") lapply(strsplit(namelist,""), function(characters, values)sum(values[characters]), values) } E.g., > f2(c("Mary Jean", "Maryjean", "Mary-Jean", "MARYJEAN")) [[1]] [1] 87 [[2]] [1] 87 [[3]] [1] 87 [[4]] [1] 87 That approach lets you map several characters to the same value, and the values are not restricted to the small positive integers 1:length(possibleCharacters). Bill Dunlap TIBCO Software Inc - Spotfire Division wdunlap tibco.com