[R] vector based command for equal values - if too slow

[jim holtman]

# no data given, so try something like this:
# split by scanID and then check for dups
dups <- lapply(split(x$ListingPrice, x$ScanID,), function(.price){
    # return sum of duplicated; non-zero => duplicated prices
    sum(duplicated(.price))
})


On Thu, Nov 12, 2009 at 12:11 PM, jorgusch <hackl.schorsch at web.de> wrote:
>
> Hi,
> I have a big set of data with price lists in different periods. I want to
> check whether there are equal prices and if so, start a loop to look closer
> into it. However, my solution so far is based on a loop and I cannot think
> of a vector based approach...any ideas?
>
> # Counting vectors
> equali<-0
> noequali<-0
> resultsi<-c()
>
> #splitting the data set
>    scanid<-xall$ScanID
>    Uscanid<-unique(scanid)
>    ULscanid<-length(Uscanid)
>
>    for(q in 1:ULscanid){
>        qscanid<-Uscanid[q]
>        x<-subset(xall, ScanID==qscanid)
>
> ## __Testing whether there are any equal prices in this ScanID
>     #-number of prices
>        xLprice<-length(x$ListingPrice)
>            if (xLprice > 1){
>
>         #-creating list of unique prices
>                xUprice<-unique(x$ListingPrice)
>                xULprice<-length(xUprice)
>
> #!!!!!!!!!!!!!!!
> #- Check whether the price are all unique or not...this takes time....
>
>                      if (xULprice==xLprice){
>                          noequali<-noequali+1
>                     }else{
>                            equali<-equali+1
>                     }
>
>
>          }
>    }#-end ScanId
>
> Well, any ideas for a vector based solution would be a great help! It would
> help the environment for sure, otherwise my machine has to run over night
> ;-)
>
> By the way, I all the efficient guys here are somehowe environmentalists -
> no offense!
> --
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> Sent from the R help mailing list archive at Nabble.com.
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?