R/calc_bfi.R

In USGS-R/EflowStats: Hydrologic Indicator and Alteration Stats

#' Function to return the base flow index for a given data frame
#' 
#' This function accepts a vector of daily mean discharge values and 
#' calculates the base flow index of the daily flow values for the entire record
#' 
#' @details The mean for a 7 day right-aligned moving window is calculated for the supplied flow vector. The baseflow index is calculated as the minimum 7day average flow divided by the mean flow
#' @param x A numeric vector of consecutive daily mean discharge values
#' @return calc_bfi numeric value of the base flow index for the given data frame
#' @export
#' @importFrom RcppRoll roll_mean
#' @examples
#' x<-sampleData$discharge
#' calc_bfi(x)
calc_bfi <- function(x) {

    day7mean <- RcppRoll::roll_mean(x, 7, align = "right")
    min7day <- min(day7mean)
    meanflow <- mean(x)
    calc_bfi <- min7day/meanflow 
  return(calc_bfi)
}