R/smwrBase_eventProcessing.R

In leppott/baytrends033: Long Term Water Quality Trend Analysis

#'Event Processing
#'
#'Computes the event number \code{eventNum}, the length of events
#'\code{eventLen}, or the sequence number for individual observations within an
#'event \code{eventSeq}.  Added from smwrBase.
#'
#' @rdname eventProcessing
#' @aliases eventLen eventNum eventSeq
#' @param event a logical vector where \code{TRUE} indicates that an event
#'occurred. Missing values are treated as instructed by \code{na.fix}.
#' @param reset a logical value indicating whether the event is assumed to
#'continue until the next event, or only while event is \code{TRUE}.
#' @param na.fix the value to use where event has missing values (\code{NA}s).
#' @param eventno an integer vector indicating the event number. Generally the
#'output from the \code{eventNum} function.
#' @param summary a logical value, controlling output. See \bold{Value} for
#'details.
#' @return The function \code{eventNum} returns an integer vector the same
#'length as \code{event} indicating the event sequence number.\cr
#'
#'The function \code{eventLen} returns an integer vector the same length as
#'\code{eventno} indicating the sequence length of the event if \code{summary}
#'is \code{FALSE}, or a named integer vector indicating the sequence length of
#'each event if \code{summary} is \code{TRUE}.\cr
#'
#'The function \code{eventSeq} returns an integer vector the same length as
#'\code{eventno} indicating the sequence number of each element in the
#'event.
#' @keywords internal manip
#' @export
#' @examples
#'
#'## Notice the difference caused by setting reset to TRUE
#'eventNum(c(TRUE,TRUE,FALSE,FALSE,TRUE,FALSE))
#'eventNum(c(TRUE,TRUE,FALSE,FALSE,TRUE,FALSE), reset=TRUE)
eventNum <- function(event, reset=FALSE, na.fix=FALSE) {
  ## Coding history:
  ##    2005????? DLLorenz Initial coding.
  ##    2006May18 DLLorenz function name changes
  ##    2007Apr05 DLLorenz Added eventLen
  ##    2011May25 DLLorenz Begin Conversion to R 
  ##    2012Aug11 DLLorenz Integer fixes
  ##    2013Feb02 DLLorenz Prep for gitHub
  ##
  event[is.na(event)] <- na.fix
  event.rle <- rle(c(event, FALSE))
  number <- 0L
  ret.val <- rep(0L, length(event) + 1L)
  i <- 1L
  beg <- 1L
  while(i < length(event.rle$values)) {
    if(event.rle$values[i]) {
      number <- number + 1L
      end <- beg + event.rle$lengths[i] + event.rle$lengths[i+1] - 1L
      ret.val[beg:end] <- number
      beg <- end + 1L
      i <- i + 2L
    } else {
      beg <- event.rle$lengths[i] + 1L # can only be 1
      i <- i + 1L
    }
  }
  ret.val <- ret.val[seq(along=event)] # remove the last value
  if(reset)
    ret.val <- ifelse(event, ret.val, 0L)
  return(ret.val)
}

#' @rdname eventProcessing
#' @export
#' @examples
#'
#'## Notice the difference caused by setting reset to TRUE
#'eventSeq(eventNum(c(TRUE,TRUE,FALSE,FALSE,TRUE,FALSE)))
#'eventSeq(eventNum(c(TRUE,TRUE,FALSE,FALSE,TRUE,FALSE), reset=TRUE))
eventSeq <- function(eventno) {
  ## Compute the sequence number within an event
  ret.val <- as.vector(unlist(apply(as.matrix(rle(eventno)$lengths),
                                    1L, function(x) seq(1L,x))))
  ret.val <- ifelse(eventno == 0L, 0L, ret.val)
  return(ret.val)
}

#' @rdname eventProcessing
#' @export
#' @examples
#'
#'## Notice the difference caused by setting reset to TRUE
#'eventLen(eventNum(c(TRUE,TRUE,FALSE,FALSE,TRUE,FALSE), reset=TRUE))
#'## This is an example of the summary option
#'eventLen(eventNum(c(TRUE,TRUE,FALSE,FALSE,TRUE,FALSE), reset=TRUE), summary=TRUE)
eventLen <- function(eventno, summary=FALSE) {
  ## Compute the length of each event
  ## if summary is desired, then return named vector of lengths
  event.rle <- rle(eventno)
  if(summary) {
    event.sel <- event.rle$values > 0L
    retval <- event.rle$lengths[event.sel]
    names(retval) <- event.rle$values[event.sel]
    return(retval)
  }
  event.rle$values <- (event.rle$values > 0L) * event.rle$length
  return(rep(event.rle$values, times=event.rle$length))
}