R/dh14.R

In jlthomps/EflowStats: Returns HIT/HAT Hydrologic Indicator stats for a given set of data

#' Function to return the DH14 hydrologic indicator statistic for a given data frame
#' 
#' This function accepts a data frame that contains a column named "discharge" and calculates 
#' DH14; Flood duration. Compute the mean of the mean monthly flow values. Find the 95th percentile for the 
#' mean monthly flows. DH14 is the 95th percentile value divided by the mean of the monthly means 
#' (dimensionless-spatial).
#' 
#' @param qfiletempf data frame containing a "discharge" column containing daily flow values
#' @return dh14 numeric containing DH14 for the given data frame
#' @export
#' @examples
#' qfiletempf<-sampleData
#' dh14(qfiletempf)
dh14 <- function(qfiletempf) {
  meanmonthly <- aggregate(qfiletempf$discharge, list(qfiletempf$month_val,qfiletempf$wy_val), mean, na.rm=TRUE)
  meanflow <- mean(meanmonthly$x)
  isolateq <- meanmonthly$x
  sortq <- sort(isolateq)
  hfcrit <- quantile(sortq,.95,type=6)
  dh14 <- hfcrit/meanflow
  return(dh14)
}