[R] maptools sunrise sunset function

From: stephen sefick <ssefick_at_gmail.com>
Date: Sat, 08 Nov 2008 19:40:11 -0500


##This is a function that I am trying to write to calculate sunrise and sunset and works "mostly", but returns nonsensical values. What am I #missing? Thanks in advance.

###remember to include maptools as dependence### library(maptools)
sunrise.set <- function(lat, long, date, timezone="UTC", num.days=1){

	#this needs to be long lat#
	lat.long <- matrix(c(long, lat), nrow=1)
	day <- as.POSIXct(date, tz=timezone)
	sequence <- seq(from=day, length.out=num.days , by="days")
	sunrise <- sunriset(lat.long, sequence, direction="sunrise", POSIXct=TRUE)
	sunset <- sunriset(lat.long, sequence, direction="sunset", POSIXct=TRUE)
	ss <- data.frame(sunrise, sunset)
	ss <- ss[,-c(1,3)]
	colnames(ss)<-c("sunrise", "sunset")
	return(ss)

}

#This doesn't make any sense
sunrise.set(33.46, 84.25, "2008-11-08", timezone="EST")

-- 
Stephen Sefick
Research Scientist
Southeastern Natural Sciences Academy

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis

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Received on Sun 09 Nov 2008 - 00:41:49 GMT

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