R/calculateMonthlyResults.R

In EGRET: Exploration and Graphics for RivEr Trends

#' Calculates monthly mean values of Q, Conc, FNConc, Flux, and FNFlux for the entire record.  If WRTDSKalman has been run it also includes the monthly mean values of GenConc and GenFlux.   
#'
#' Computes the monthly mean values of discharge, concentration, flux, flow-normalized concentration and flow-normalized flux (Q, Conc, FNConc, Flux, and FNFlux) in SI units
#' If WRTDSKalman has been run the outputs are averages for Q, Conc, GenConc, FNConc, Flux, GenFlux, and FNFlux. 
#' Note that the Flux, GenFlux, and FNFlux values are average flux values (not totals). For discharge the units are in m3/s, concentration is mg/L, and flux is kg/day.
#' It returns a data frame containing month, year, decimal year, and mean values of DecYear, Q, Conc, GenConc, FNConc, Flux, GenFlux, and FNFlux.
#'
#' @param eList named list with at least the Daily dataframes
#' @keywords water-quality statistics
#' @return MonthlyResults data frame of numeric values describing the monthly average values
#' @export
#' @examples
#' eList <- Choptank_eList
#' monthlyResults <- calculateMonthlyResults(eList)
calculateMonthlyResults <- function(eList){
  
  localDaily <- getDaily(eList)

  nDays <- aggregate(localDaily$ConcDay, by=list(localDaily$MonthSeq), function(x) sum(!is.na(x)))$x

  Q <- aggregate(localDaily$Q, by=list(localDaily$MonthSeq), mean)$x
  DecYear <- aggregate(localDaily$DecYear, by=list(localDaily$MonthSeq), mean)$x
  Year <- trunc(DecYear)
  Month <- aggregate(localDaily$Month, by=list(localDaily$MonthSeq), mean)$x
  Conc <- aggregate(localDaily$ConcDay, by=list(localDaily$MonthSeq), mean)$x
  Flux <- aggregate(localDaily$FluxDay, by=list(localDaily$MonthSeq), mean)$x
  FNConc <- aggregate(localDaily$FNConc, by=list(localDaily$MonthSeq), mean)$x
  FNFlux <- aggregate(localDaily$FNFlux, by=list(localDaily$MonthSeq), mean)$x

  kalman <- all(c("GenConc","GenFlux") %in% names(localDaily))
  
  if(kalman){
    GenConc <- aggregate(localDaily$GenConc, by=list(localDaily$MonthSeq), mean)$x
    GenFlux <- aggregate(localDaily$GenFlux, by=list(localDaily$MonthSeq), mean)$x

    MonthlyResults <- data.frame(Month, Year, nDays,
                                 DecYear, Q,
                                 Conc, GenConc, FNConc,  
                                 Flux, GenFlux, FNFlux)
                                     
  } else {
    MonthlyResults <- data.frame(Month, Year, nDays,
                                 DecYear, Q,
                                 Conc, FNConc, 
                                 Flux, FNFlux)  
  }
  
  MonthlyResults <- MonthlyResults[(nDays > 15),]
  
  return(MonthlyResults)
}