S3 methods for streaming modelling with R package stream and for data in an ffdf

gistfile1.r

DSD_FFDFstream <- function(x, k=NA, assignment=NULL, loop=FALSE) {
  stopifnot(is.ffdf(x))
  open(x)
  state <- new.env()
  assign("counter", 1L, envir = state) 
  l <- list(description = "FF Data Stream",
            strm = x,
            state = state,
            d = ncol(x),
            k = k,           
            assignment = assignment,
            loop = loop)
  class(l) <- c("DSD_FFDFstream","DSD_R","DSD") 
  l
}
 
get_points.DSD_FFDFstream <- function(x, ...){
  stream:::get_points.DSD_Wrapper(x, ...)
}
print.DSD_FFDFstream <- function(x, ...) {
  NextMethod() # calling the super classes print()
  pos <- x$state$counter
  if (pos>nrow(x$strm))
    if (!x$loop) pos <- "'end'" else pos <- 1
  cat(paste('Contains', nrow(x$strm),
            'data points - currently at position', pos,
            '- loop is', x$loop, '\n'))
}
reset_stream.DSD_FFDFstream <- function(dsd) {
  stream:::reset_stream.DSD_Wrapper(dsd)
}