[R] sampling dataframe based upon number of record occurrences

[JS Huang]

Since you indicated there are six more columns in the data.frame, getSample
modified below to take care of it.

> getSample
function(x)
{
  sites <- unique(x$SiteID)
  years <- unique(x$Year)
  result <- data.frame()
  x$ID <- seq(1,nrow(x))
  for (i in 1:length(sites))
  {
    for (j in 1:length(years))
    {
      if (nrow(x[as.character(x$SiteID)==as.character(sites[i]) &
x$Year==years[j],]) > 3)
      {
        sampledID <- sample(x[as.character(x$SiteID)==as.character(sites[i])
& x$Year==years[j],]$ID,3,replace=FALSE)
        for (k in 1:length(sampledID))
        {
          result <- rbind(result,x[x$ID==sampledID[k],-ncol(x)])
        }          
      }
    }
  }
  names(result) <- names(x)[-ncol(x)]
  rownames(result) <- NULL
  return(result)
}
> getSample(fitting.set)
  IDbyYear    SiteID Year
1    42.24 A-Airport 2006
2    42.24 A-Airport 2006
3    42.24 A-Airport 2006




--
View this message in context: http://r.789695.n4.nabble.com/sampling-dataframe-based-upon-number-of-record-occurrences-tp4704144p4704155.html
Sent from the R help mailing list archive at Nabble.com.