[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")


#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

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annoying little problems of being mammals.

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

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