Function to discriminate between periods of residency and movement based on
consecutive sunrise and sunset data. The calculation is based on a
changepoint model (R Package changepoint:
cpt.mean) to find multiple changepoints within the
data.
vector of sunrise/sunset times (e.g. 2008-12-01 08:30).
tSecond
vector of of sunrise/sunset times (e.g. 2008-12-01 17:30).
type
vector of either 1 or 2, defining tFirst as sunrise or sunset respectively.
twl
data.frame containing twilights and at least tFirst, tSecond and type (alternatively give each parameter separately).
quantile
probability threshold for stationary site selection. Higher
values (above the defined quantile of all probabilities) will be considered
as changes in the behavior. Argmuent will only be considered if either rise.prob and/or
set.prob remain unspecified.
rise.prob
the probability threshold for sunrise: greater or
equal values indicates changes in the behaviour of the individual.
set.prob
the probability threshold for sunset: higher and
equal values indicates changes in the behaviour of the individual.
days
a threshold for the length of stationary period. Periods smaller
than "days" will not be considered as a residency period
plot
logical, if TRUE a plot will be produced
summary
logical, if TRUE a summary of the results will be
printed
Details
The cpt.mean from the R Package changepoint is a
function to find a multiple changes in mean for data where no assumption is
made on their distribution. The value returned is the result of finding the
optimal location of up to Q changepoints (in this case as many as possible)
using the cumulative sums test statistic.
Value
A list with probabilities for sunrise and
sunset the user settings of the probabilities and the resulting
stationary periods given as a vector, with the residency sites as
positiv numbers in ascending order (0 indicate movement/migration).
Note
The sunrise and/or sunset times shown in the graph (if
plot=TRUE) represent hours of the day. However if one or both of the
twilight events cross midnight during the recording period the values will
be formed to avoid discontinuity.
Author(s)
Simeon Lisovski & Tamara Emmenegger
References
Taylor, Wayne A. (2000) Change-Point Analysis: A Powerful New
Tool For Detecting Changes.
M. Csorgo, L. Horvath (1997) Limit Theorems in Change-Point Analysis.
Wiley.
Chen, J. and Gupta, A. K. (2000) Parametric statistical change point
analysis. Birkhauser.
R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.
R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.
Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.
> library(GeoLight)
Loading required package: maps
# maps v3.1: updated 'world': all lakes moved to separate new #
# 'lakes' database. Type '?world' or 'news(package="maps")'. #
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/GeoLight/changeLight.Rd_%03d_medium.png", width=480, height=480)
> ### Name: changeLight
> ### Title: Residency analysis using a changepoint model
> ### Aliases: changeLight
>
> ### ** Examples
>
> data(hoopoe2)
> hoopoe2$tFirst <- as.POSIXct(hoopoe2$tFirst, tz = "GMT")
> hoopoe2$tSecond <- as.POSIXct(hoopoe2$tSecond, tz = "GMT")
> residency <- changeLight(hoopoe2, quantile=0.9)
Probability threshold(s):
Sunrise: 0.03757 Sunset: 0.01307
Migration schedule table:
Site Arrival Departure Days P.start P.end
1 a 2008-07-15 23:34:00 2008-07-24 23:32:30 9.0 0.010416667 0.008333333
2 b 2008-07-31 00:15:00 2008-08-19 12:26:00 19.5 0.010500257 0.000000000
3 c 2008-08-25 00:25:30 2008-09-01 12:20:00 7.5 0.008333333 0.006995885
4 d 2008-09-12 12:27:30 2008-10-02 12:28:00 20.0 0.006321499 0.000000000
5 e 2008-10-03 12:22:30 2008-10-19 12:26:00 16.0 0.004629630 0.000000000
6 f 2008-10-20 12:22:00 2008-12-03 12:35:30 44.0 0.000000000 0.006198347
7 g 2008-12-04 12:28:30 2008-12-18 12:32:00 14.0 0.000000000 0.010706019
8 h 2008-12-19 12:41:00 <NA> NA 0.005729167 0.000000000
Days.1 P.start.1
1 9.0 0.010416667
2 19.5 0.010500257
3 7.5 0.008333333
4 20.0 0.006321499
5 16.0 0.004629630
6 44.0 0.000000000
7 14.0 0.000000000
8 NA 0.005729167
>
>
>
>
>
> dev.off()
null device
1
>