R/to_hist_percentile.R

In USGS-R/soilmoisturetools: USGS Soil Moisture Portal tools

#'@title Convert values to historical percentile
#'
#'@param data A data frame from one of the service functions (e.g., \link{ok_data})
#'
#'
#'
#'
#'
#'
#'@export
to_hist_percentile = function(data){
	
	id_strings = strsplit(data$station[1], ':')[[1]]
	service = id_strings[3]
	
	fpath = switch(toupper(service), 
							 TX_MESO = "WestTexas_Coefficients.csv", 
							 OK_MESO = "Oklahoma_mesonet.csv",
							 SCAN    = "SCAN_Coefficients.csv",
							 CRN     = "CRN_Coefficients.csv",
							 'error'
							 )
	
	
	#make sure we got a match
	if(fpath == 'error'){
		stop('unrecognized state in station ids')
	}
	
	coeff = load_coefficients(fpath)
	
	data$month = as.POSIXlt(data$datetime)$mon+1
	#data$depth_cm = floor(data$depth_in*2.54) #convert to CM for better matching
	data$station_id = sapply(strsplit(data$station, ':'), function(x){x[1]})
	
	
	data = merge(data, coeff, by=c('station_id', 'month', 'depth_cm'))
	
	data$vol_value = data$value
	values = data$value/100
	data$value = data$c4*values^4 + data$c3*values^3 + data$c2*values^2 + data$c1*values + data$c0
	
	data$value = data$value * 100
	
	return(data[, c('station', 'datetime', 'value', 'vol_value', 'depth_cm')])
	
}


load_coefficients = function(fpath){
	
	pkg_path = system.file(paste0('extdata/historical_prct_coeff/', fpath), package=packageName())
	
	coeff = read.csv(pkg_path, header=FALSE, comment.char = "")
	names(coeff) = c('station_id', 'depth_cm', 'month', 'c4', 'c3', 'c2', 'c1', 'c0')
	return(coeff)
}