Examples for 'maptools::crepuscule'

Methods for sun ephemerides calculations

Aliases: crepuscule sunriset solarnoon solarpos crepuscule-methods crepuscule,SpatialPoints,POSIXct-method crepuscule,matrix,POSIXct-method solarnoon-methods solarnoon,SpatialPoints,POSIXct-method solarnoon,matrix,POSIXct-method solarpos-methods solarpos,SpatialPoints,POSIXct-method solarpos,matrix,POSIXct-method sunriset-methods sunriset,SpatialPoints,POSIXct-method sunriset,matrix,POSIXct-method

Keywords: methods manip utilities

### ** Examples

## Location of Helsinki, Finland, in decimal degrees,
## as listed in NOAA's website
hels <- matrix(c(24.97, 60.17), nrow=1)
Hels <- SpatialPoints(hels, proj4string=CRS("+proj=longlat +datum=WGS84"))
d041224 <- as.POSIXct("2004-12-24", tz="EET")
## Astronomical dawn
crepuscule(hels, d041224, solarDep=18, direction="dawn", POSIXct.out=TRUE)

       day_frac                time
newlon   0.2762 2004-12-24 06:37:43

crepuscule(Hels, d041224, solarDep=18, direction="dawn", POSIXct.out=TRUE)

       day_frac                time
newlon   0.2762 2004-12-24 06:37:43

## Nautical dawn
crepuscule(hels, d041224, solarDep=12, direction="dawn", POSIXct.out=TRUE)

        day_frac                time
newlon 0.3121822 2004-12-24 07:29:32

crepuscule(Hels, d041224, solarDep=12, direction="dawn", POSIXct.out=TRUE)

        day_frac                time
newlon 0.3121822 2004-12-24 07:29:32

## Civil dawn
crepuscule(hels, d041224, solarDep=6, direction="dawn", POSIXct.out=TRUE)

        day_frac                time
newlon 0.3519249 2004-12-24 08:26:46

crepuscule(Hels, d041224, solarDep=6, direction="dawn", POSIXct.out=TRUE)

        day_frac                time
newlon 0.3519249 2004-12-24 08:26:46

solarnoon(hels, d041224, POSIXct.out=TRUE)

        day_frac                time
newlon 0.5137966 2004-12-24 12:19:52

solarnoon(Hels, d041224, POSIXct.out=TRUE)

        day_frac                time
newlon 0.5137966 2004-12-24 12:19:52

solarpos(hels, as.POSIXct(Sys.time(), tz="EET"))

         [,1]     [,2]
[1,] 274.8815 14.66269

solarpos(Hels, as.POSIXct(Sys.time(), tz="EET"))

         [,1]     [,2]
[1,] 274.8815 14.66268

sunriset(hels, d041224, direction="sunrise", POSIXct.out=TRUE)

        day_frac                time
newlon 0.3924249 2004-12-24 09:25:05

sunriset(Hels, d041224, direction="sunrise", POSIXct.out=TRUE)

        day_frac                time
newlon 0.3924249 2004-12-24 09:25:05

## Using a sequence of dates
Hels_seq <- seq(from=d041224, length.out=365, by="days")
up <- sunriset(Hels, Hels_seq, direction="sunrise", POSIXct.out=TRUE)
down <- sunriset(Hels, Hels_seq, direction="sunset", POSIXct.out=TRUE)
day_length <- down$time - up$time
plot(Hels_seq, day_length, type="l")
plot of chunk example-maptools-crepuscule-1
## Using a grid of spatial points for the same point in time
## Not run: 
##D grd <- GridTopology(c(-179,-89), c(1,1), c(359,179))
##D SP <- SpatialPoints(coordinates(grd),
##D                     proj4string=CRS("+proj=longlat +datum=WGS84"))
##D wint <- as.POSIXct("2004-12-21", tz="GMT")
##D win <- crepuscule(SP, wint, solarDep=6, direction="dawn")
##D SPDF <- SpatialGridDataFrame(grd,
##D  proj4string=CRS("+proj=longlat +datum=WGS84"),
##D  data=data.frame(winter=win))
##D image(SPDF, axes=TRUE, col=cm.colors(40))
## End(Not run)
[Package maptools version 1.1-4 Index]