[R] string parsing

[Mike Marchywka]

----------------------------------------
> To: r-help at stat.math.ethz.ch
> From: sds at gnu.org
> Date: Tue, 15 Feb 2011 17:20:11 -0500
> Subject: [R] string parsing
>
> I am trying to get stock metadata from Yahoo finance (or maybe there is
> a better source?)

search this for "yahoo",

http://cran.r-project.org/web/packages/quantmod/quantmod.pdf

as a perennial page scraper, I was amazed this existed :)


> here is what I did so far:
>
> yahoo.url <- "http://finance.yahoo.com/d/quotes.csv?f=j1jka2&s=";
> stocks <- c("IBM","NOIZ","MSFT","LNN","C","BODY","F"); # just some samples
> socket <- url(paste(yahoo.url,sep="",paste(stocks,collapse="+")),open="r");
> data <- read.csv(socket, header = FALSE);
> close(socket);
> data is now:
> V1 V2 V3 V4
> 1 200.5B 116.00 166.25 4965150
> 2 19.1M 3.75 5.47 8521
> 3 226.6B 22.73 31.58 57127000
> 4 886.4M 30.80 74.54 226690
> 5 142.4B 3.21 5.15 541804992
> 6 276.4M 11.98 21.30 149656
> 7 55.823B 9.75 18.97 89369000
>
> now I need to do this:
>
> --> convert 55.823B to 55e9 and 19.1M to 19e6
>
> parse.num <- function (s) { as.numeric(gsub("M$","e6",gsub("B$","e9",s))); }
> data[1]<-lapply(data[1],parse.num);
>
> seems like awfully inefficient (two regexp substitutions),
> is there a better way?
>
> --> iterate over stocks & data at the same time and put the results into
> a hash table:
> for (i in 1:length(stocks)) cache[[stocks[i]]] <- data[i,];
>
> I do get the right results,
> but I am wondering if I am doing it "the right R way".
> E.g., the hash table value is a data frame.
> A structure(record?) seems more appropriate.
>
> thanks!
>
> --
> Sam Steingold (http://sds.podval.org/) on CentOS release 5.3 (Final)
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>
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