solartime (version 0.0.4)

computeIsDayByLocation: computeIsDayByLocation

Description

tell for each timestamp, whether its daytime

Usage

computeIsDayByLocation(timestamp, latDeg, 
    longDeg, timeZone = getHoursAheadOfUTC(timestamp), 
    duskOffset = 0, isCorrectSolartime = TRUE)

Value

logical vector (length(date)): true if its daytime

Arguments

timestamp

POSIXct vector

latDeg

Latitude in (decimal) degrees

longDeg

Longitude in (decimal) degrees

timeZone

Time zone (in hours) ahead of UTC (Central Europe is +1)

duskOffset

integer scalar: time in hours after dusk for which records are still regarded as day

isCorrectSolartime

set to FALSE to omit correction between local time and solar time, e.g. if coordinates cannot be provided

Author

Thomas Wutzler

Details

computes hour of sunrise and sunset from given date in timezone hour (assuming dates are given in timezone instead of solartime)

Examples

dateSeq <- seq( as.POSIXct("2017-03-20", tz = "Etc/GMT-1")
                ,as.POSIXct("2017-03-21", tz = "Etc/GMT-1")
                , by = "30 min")
tmp <- computeIsDayByLocation(
  dateSeq, latDeg = 50.93, longDeg = 11.59, timeZone = 1)
plot( tmp ~ dateSeq )
yday <- as.POSIXlt(dateSeq[1])$yday + 1L
sunrise <- computeSunriseHourDoy(
  yday, latDeg = 50.93, longDeg = 11.59, timeZone = 1)
sunset <- computeSunsetHourDoy(
  yday, latDeg = 50.93, longDeg = 11.59, timeZone = 1)
abline( v = trunc(dateSeq[1], units = "days") + c(sunrise,sunset)*3600L )