R/getSWATdates.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>, March 2015                           #
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# 					           *** Version 1.0.2 *** 										  #
#								Date conversion function		                              #
#				converts common date formats to SWAT weather input date format 'yyyyddd'      #                     
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#' Converts a date time series to SWAT IO format dates
#' @param dates
#' @param dateformat
#' @return returns a time series of swat IO format dates from the input
#' @export 




getSWATdates <- function(dates, dateformat = 'yyyy-mm-dd'){
	
if(dateformat == 'yyyy-mm-dd'){
	dateformat <- c('year', 'month', 'day')
	colsep <- '-'
} else if(format == 'mm-dd-yyyy'){
	dateformat <- c('month', 'day', 'year')
	colsep <- '-'
} else if(format == 'mm/dd/yyyy'){
	dateformat <- c('month', 'day', 'year')
	colsep <- '/'
} else if(format == 'yyyy/mm/dd'){
	dateformat <- c('year', 'month', 'day')
	colsep <- '/'
} else if(format == 'dd/mm/yyy'){
	dateformat <- c('day', 'month', 'year')
	colsep <- '/'
}else if(format == 'dd-mm-yyy'){
	dateformat <- c('day', 'month', 'year')
	colsep <- '/'
}else {
	stop(c("Bad Date format", "use 'yyyy-mm-dd', 'yyyy/mm/dd', 'mm-dd-yyyy', 'dd/mm/yyy', 'dd-mm-yyy' or 'mm-dd-yyyy\n'", "Make sure input matches one of these formats and 'dateformat' is set accordingly"))
}


####added from original code to satisfy the colsplit requirement of character object. #remember as.___ does NOT coerce, it needs a to be set to a object
dates1 <- as.character(dates)


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datesm <- data.frame(matrix(nrow <- length(dates1), ncol <- 3))

datessplit <- strsplit(dates1, colsep)

for(i in 1:length(dates1)){
	datesm[i,1] <- datessplit[[i]][1] 
	datesm[i,2] <- datessplit[[i]][2]
	datesm[i,3] <- datessplit[[i]][3] 

}

dates1 <- data.frame(datesm, stringsAsFactors <- FALSE)

dates1[,1] <- as.numeric(dates1[,1])
dates1[,2] <- as.numeric(dates1[,2])
dates1[,3] <- as.numeric(dates1[,3])

dates1 <- as.data.frame(dates1)

colnames(dates1) <- c(dateformat)

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#Create the 2nd to last data frame for dates 
dates.format <- data.frame(matrix(ncol = 2, nrow = nrow(dates1)))
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(i in 1:100){
		year <- year+ (1*4)
		leap.years[i] <- year
}

ln.leap.years <- length(leap.years)

for(i in 1:ln.leap.years){
	if(dates1$year[1] == leap.years[i]){
		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(i in 1:nrow(dates1)){
	month <- dates1$month[i]
	for(j in 1:12){
		if(month == add.days$month[j]){
			ex.day <- add.days$days[j]
		}
	extra.days[i] <- ex.day
	}
}


#fill out the day column of dates.format 
dates.format$days <- dates1$day + extra.days
dates.format$year <- dates1$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)

}