sunTime | R Documentation |

Converts a vector of clock times to "sun times", by mapping sunrise to `\pi/2`

and sunset to `3\pi/2`

. Sunrise and sunset times are determined based on the dates and locations provided. See Nouvellet et al (2012) for a discussion. Requires the suntools package.

```
sunTime(clockTime, Dates, Coords)
```

`clockTime` |
a vector of times of observations in |

`Dates` |
a POSIXct object with the dates of the observations; the time zone must be set to the time zone used for 'clockTime'. |

`Coords` |
a SpatialPoints object with the locations of the observations, or with a single point giving a approximate location for the study area; the coordinates must be geographical coordinates, eg, WGS84, with long before lat. |

Returns a vector of "sun times" in *radians*, where `\pi/2`

corresponds to sunrise and `3\pi/2`

to sunset.

Mike Meredith.

Nouvellet et al (2012) Noisy clocks and silent sunrises: measurement methods of daily activity pattern. *Journal of Zoology* 286:179-184.

```
# Check that sp and suntools packages are installed
if(requireNamespace("sp") && requireNamespace("suntools")) {
# Get example data:
data(simCalls)
str(simCalls)
# Convert dates to a POSIXct object with the right time zone (GMT):
Dates <- as.POSIXct(simCalls$dates, tz="GMT")
# Create a SpatialPoints object with the location
coords <- matrix(c(-3, 56), nrow=1)
Coords <- sp::SpatialPoints(coords, proj4string=sp::CRS("+proj=longlat +datum=WGS84"))
st <- sunTime(simCalls$time, Dates, Coords)
exPar<-par(mfrow=c(2,1))
densityPlot(st, col='red', lwd=2, xaxt='n', main="Sun time")
axis(1, at=c(0, 6, 12, 18, 24),
labels=c("midnight", "sunrise", "noon", "sunset", "midnight"))
densityPlot(simCalls$time, lwd=2, main="Clock time")
par(exPar)
}
```

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