is.sd {adehabitat} | R Documentation |
is.sd
tests whether the bursts of relocations in an object of
class ltraj
contain the same number of relocations, and cover
the same duration ("sd" = "same duration").
sd2df
gets one of the descriptive parameters of a regular "sd"
trajectory (e.g. "dt"
, "dist"
, etc.) and returns a data
frame with one relocation per row, and one burst per column.
is.sd(ltraj) sd2df(ltraj, what)
ltraj |
an object of class ltraj |
what |
a character string indicating the descriptive parameter of the trajectory to be exported |
is.sd
returns a logical value.
sd2df
returns a data frame with one column per burst of
relocations, and one row per relocation.
Clement Calenge clement.calenge@oncfs.gouv.fr
set.limits
for additional information about
"sd" regular trajectories
## Takes the example from the help page of cutltraj (bear): data(bear) ## We want to study the trajectory of the animal at the scale ## of the day. We define one trajectory per day. The trajectory should begin ## at 22H00. ## The following function returns TRUE if the date is comprised between ## 21H00 and 22H00 and FALSE otherwise (i.e. correspond to the ## relocation taken at 21H30) foo <- function(date) { da <- as.POSIXlt(date, "GMT") ho <- da$hour + da$min/60 return(ho>21.1&ho<21.9) } ## We cut the trajectory into bursts after the relocation taken at 21H30: bea1 <- cutltraj(bear, "foo(date)", nextr = TRUE) bea1 ## Remove the first and last burst: bea2 <- bea1[-c(1,length(bea1))] ## Is the resulting object "sd" ? is.sd(bea2) ## Converts to data frame: df <- sd2df(bea2, "dist") ## Plots the average distance per hour meandi <- apply(df[-nrow(df),], 1, mean, na.rm = TRUE) sedi <- apply(df[-nrow(df),], 1, sd, na.rm = TRUE) / sqrt(ncol(df)) plot(seq(0, 23.5, length = 47), meandi, ty = "b", pch = 16, xlab = "Hours (time 0 = 22H00)", ylab="Average distance covered by the bear in 30 mins", ylim=c(0, 500)) lines(seq(0, 23.5, length = 47), meandi+sedi, col="grey") lines(seq(0, 23.5, length = 47), meandi-sedi, col="grey")