#' Function to return the TH3 hydrologic indicator statistic for a given data frame
#'
#' This function accepts a data frame that contains a column named "discharge" and
#' calculates the predictability of flow below the 60th percentile for the entire record
#'
#' @param qfiletempf data frame containing a "discharge" column containing daily flow values
#' @return tl4 numeric containing the ratio of maximum duration across years of flow below the 60th pctl to days in the year for the given data frame
#' @export
#' @examples
#' load_data<-paste(system.file(package="HITHATStats"),"/data/obs_data.csv",sep="")
#' qfiletempf<-read.csv(load_data)
#' th3(qfiletempf)
th3 <- function(qfiletempf) {
isolateq <- qfiletempf$discharge
sortq <- sort(isolateq)
frank <- floor(findrank(length(sortq), 0.40))
lfcrit <- sortq[frank]
qfiletempf$diff <- (qfiletempf$discharge-lfcrit)
jul_day_sum <- aggregate(qfiletempf$diff, list(qfiletempf$jul_val), sum)
maxdur <- rep(0,nrow(jul_day_sum))
flag <- 0
for (i in 1:365) {
if (!is.na(jul_day_sum$x[i])==TRUE) {
if (jul_day_sum$x[i]<=0) {
flag <- flag+1
maxdur[i]<-flag
}} else {
maxdur[i] <- 0
}
}
th3 <- max(maxdur)/365
return(th3)
}
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