[R] string parsing

[David Winsemius]

On Feb 16, 2011, at 2:09 PM, Sam Steingold wrote:

>> * David Winsemius <qjvafrzvhf at pbzpnfg.arg> [2011-02-16 13:33:32  
>> -0500]:
>>
>>> parse.num <- function (s) {
>>> as.numeric(gsub("M$","e6",gsub("B$","e9",s))); }
>>
>> data[1] <- parse.num( data[[1]] )  # as.numeric and gsub are  
>> vectorized
>
> because parse.num turned out to not be as simple as that: I need to
> handle "N/A" specially.
>
> parse.num1 <- function (s) {
>  if (length(s) != 1) stop("parse.num",s);
>  s <- as.character(s);
>  if (s == "N/A") return(NA);

Ouch! That can be simplified to:

    #  and then all done inside one function.

>  as.numeric(gsub("M$","e6",gsub("B$","e9",s)));
> }
>
> parse.num <- function (v) {
>  for (i in 1:length(v)) v[[i]] <- parse.num1(v[[i]])
>  v;
> }
>
> actually... wait a sec...
> shouldn't this work?
>
>  bad <- (data[1] == "N/A")
>  data[1][bad] <- NA
>  data[1][!bad] <- as.numeric(gsub("M$","e6",gsub("B$","e9",data[1])))

It might not, since at this point you should have different length  
vectors.

(I'm also not sure that the  listobj[<n>][<logical>] <- <vector>  
construction would work, but I really don't know about that one.)

parse.num2 <- function (s) {
  is.na(s) <- (s == "N/A")
  as.numeric(gsub("M$","e6",gsub("B$","e9",s)))
       }

Then call as I suggested


>
>
> -- 
> Sam Steingold (http://sds.podval.org/) on CentOS release 5.3 (Final)
> http://dhimmi.com http://memri.org http://truepeace.org http://camera.org
> http://thereligionofpeace.com http://palestinefacts.org http://www.memritv.org
> Heck is a place for people who don't believe in gosh.

David Winsemius, MD
West Hartford, CT