R/RProjects/HITHATStats/R/ml1.12.R

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

#' Function to return the ML1-ML12 hydrologic indicator statistics for a given data frame
#' 
#' This function accepts a data frame that contains columns named "discharge", "year_val" and "month_val" and 
#' calculates the mean minimum flows for each month across all years. 
#' Compute the minimums for each month. For example, ML1 is the mean of the minimums of all January flow values.
#' 
#' @param qfiletemp data frame containing a "discharge" column containing daily flow values
#' @return ml1.12 data frame containing the mean or medians for each month
#' @export
#' @examples
#' load_data<-paste(system.file(package="HITHATStats"),"/data/obs_data.csv",sep="")
#' qfiletemp<-read.csv(load_data)
#' ml1.12(qfiletemp)
ml1.12 <- function(qfiletemp) {
  minbymonyr <- aggregate(qfiletemp$discharge, list(qfiletemp$year_val, qfiletemp$month_val), FUN = min, na.rm=TRUE)
  colnames(minbymonyr) <- c("Year","Month","minmo")
  meanminbymon <- aggregate(minbymonyr$minmo, list(minbymonyr$Month), FUN = mean, na.rm=TRUE)
  colnames(meanminbymon) <- c("Month","meanmin")
  ml1 <- meanminbymon[1,2]
  ml2 <- meanminbymon[2,2]
  ml3 <- meanminbymon[3,2]
  ml4 <- meanminbymon[4,2]
  ml5 <- meanminbymon[5,2]
  ml6 <- meanminbymon[6,2]
  ml7 <- meanminbymon[7,2]
  ml8 <- meanminbymon[8,2]
  ml9 <- meanminbymon[9,2]
  ml10 <- meanminbymon[10,2]
  ml11 <- meanminbymon[11,2]
  ml12 <- meanminbymon[12,2]
  ml1.12 <- list(ml1,ml2,ml3,ml4,ml5,ml6,ml7,ml8,ml9,ml10,ml11,ml12)
  return(ml1.12)
}