R/genSWATdates.R

In hydroMet: Meteorological Data for Hydrological Modeling

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#          *** Copyright (C) Andrew Sommerlot - All Rights Reserved ***           					  #
# Unauthorized Copying, Distrubution, or editing of this file, via any medium is strictly prohibited  #
#                               Proprietary and Confidential                                          #
#               Written by Andrew R Sommerlot <andrewrs@vt.edu>, Februrary 2015                       #
#######################################################################################################


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# 					           *** Version 0.1.0 *** 										    #
# *This code is designed to generate a SWAT daily time sereis of date labels in the form        # 
# 	 takes yyyy-mm-dd format as input                                                           #
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#' generates a vector of dates in the swat model IO format
#' @param startDate
#' @param endDate
#' @return returns a generated time series of swat IO format dates 
#' @export 



genSWATdates <- function(startDate, endDate){


#get the single date
date <- as.Date(startDate)

#calculate the length of the generated date file
edate <- as.Date(endDate)

length <- edate - date

dates <- seq.Date(date, length.out <- length + 1, by <- 'day')

dates <- as.character(dates)

#The dates must be converted to the proper format and added to the 
dates <- data.frame(dates, stringsAsFactors <- FALSE)

#separtate dates out and leave time behind
dates <- colsplit(dates$dates, '-', c('year', 'month', 'day'))

#Create the 2nd to last data frame for dates 
dates.format <- data.frame(matrix(ncol <- 2, nrow <- nrow(dates)))
colnames(dates.format) <- c('year', 'days')

#create the add days matrix. this defines how many extra days are added given the month 
add.days <- data.frame(matrix(ncol <- 2, nrow <- 12))
colnames(add.days) <- c('month', 'days')

#define the months and corresponing extra days to add. ex.days is calculated by placing the amount of days from the ith-1 month. 
ex.days <- c(0,31,59,90,120,151,181,212,243,273,304,334)
months <- c(1,2,3,4,5,6,7,8,9,10,11,12)

#To take care of the leap year change: 
leap.years <- vector()
leap.years <- as.numeric(leap.years)
year <- 1900
for(j in 1:900){
		year <- year+ (1*4)
		leap.years[j] <- year
}
	
ln.leap.years <- length(leap.years)

for(k in 1:ln.leap.years){
	if(dates$year[1] == leap.years[k]){
		ex.days[3] <- 29
	}
}

#fill in add.days
add.days$month <- months
add.days$days <- ex.days



extra.days <- vector()
extra.days <- as.numeric(extra.days)
ex.day <- 1

#define extra days and fill in the days in dates.format 
for(l in 1:nrow(dates)){
	month <- dates$month[l]
	for(m in 1:12){
		if(month == add.days$month[m]){
			ex.day <- add.days$days[m]
		}
	extra.days[l] <- ex.day
	}
}


#fill out the day column of dates.format 
dates.format$days <- dates$day + extra.days
dates.format$year <- dates$year

#format the day column to '000' format
dates.format$days <- formatC(dates.format$days, width <- 3, flag <- '0')

#create new column in dates.format that is equivalent to the SWAT date
dates.format$fullDate <- paste(dates.format$year, dates.format$days, sep <- "")
date.full <- dates.format$fullDate
	
return(date.full)

}