trajectories (version 0.2-1)

reTrack: Reconstruct objects of class "Track"

Description

Function reTrack accepts X as an object of class "Track". Output is a reconstructed Track (again an object of class Track), based on a regular "timestamp". It only returns the interpolated points.

Usage

reTrack(X,at=c("track","dfrm"),timestamp=timestamp,tsq=NULL)

Arguments

X

an object of class Track

at

to set the type of output as either an object of class "Track" or data.frame

timestamp

timestamp which Track be reconstructed based on

tsq

a time sequence to reconstruct Track X based on it. This is optional. If this is not given, the function creates the time sequance based on timestamp.

Value

Either an object of class "Track" or a data.frame

Details

Sometimes tracks data are not collected according to a regular timestamp. In order to compare different tracks which share some time intervals, we might need to be aware of the locations in a regular timestamp. Function reTrack unables us to reconstruct an object of class "Track" based on a regular timestamp. Time sequance can be given by user, if not reTrack creates a regulare time sequance based on the given timestamp.

See Also

rTrack, as.Track, as.POSIXct, compare

Examples

# NOT RUN {
library(sp)
library(spacetime)
t0 = as.POSIXct(as.Date("2013-09-30",tz="CET"))
# person A, track 1:
x = c(7,6,5,5,4,3,3)
y = c(7,7,6,5,5,6,7)
n = length(x)
set.seed(131)
t = t0 + cumsum(runif(n) * 60)
require(rgdal)
crs = CRS("+proj=longlat +ellps=WGS84") # longlat
stidf = STIDF(SpatialPoints(cbind(x,y),crs), t, data.frame(co2 = rnorm(n)))
A1 = Track(stidf)
reTrack(A1,timestamp = "1 sec")

# }