Class "STTDF"
A class for spatio-temporal trajectory data
## S4 method for signature 'STTDF,ltraj' coerce(from, to, strict=TRUE) ## S4 method for signature 'ltraj,STTDF' coerce(from, to, strict=TRUE)
from |
from object |
to |
target class |
strict |
ignored |
Objects of this class carry sparse (irregular) space/time data
sp:Object of class "Spatial", containing the bounding
box of all trajectories
time:Object of class "xts", containing the temporal
bounding box of all trajectories
traj:Object of class list, each element holding
an STI object reflecting a single trajectory;
data:Object of class data.frame, which holds
the data values for each feature in each trajectory
signature(x = "STTDF"): select trajectories, based
on index, or spatial and/or temporal predicates
The data.frame needs to have a column called
burst which is a factor (or character) and contains the
grouping of observations that come from a continuous sequence of
observations. In addition, a column id is used to identify
individual items.
Edzer Pebesma, edzer.pebesma@uni-muenster.de
https://www.jstatsoft.org/v51/i07/
library(sp)
m = 3# nr of trajectories
n = 100 # length of each
l = vector("list", m)
t0 = as.POSIXct("2013-05-05",tz="GMT")
set.seed(1331) # fix randomness
for (i in 1:m) {
x = cumsum(rnorm(n))
y = cumsum(rnorm(n))
sp = SpatialPoints(cbind(x,y))
#t = t0 + (0:(n-1) + (i-1)*n) * 60
t = t0 + (0:(n-1) + (i-1)*n/2) * 60
l[[i]] = STI(sp, t)
}
stt= STT(l)
sttdf = STTDF(stt, data.frame(attr = rnorm(n*m), id = paste("ID", rep(1:m, each=n))))
x = as(stt, "STI")
stplot(sttdf, col=1:m, scales=list(draw=TRUE))
stplot(sttdf, by = "id")
stplot(sttdf[1])
stplot(sttdf[1])
# select a trajectory that intersect with a polygon
p = Polygon(cbind(x=c(-20,-15,-15,-20,-20),y=c(10,10,15,15,10)))
pol=SpatialPolygons(list(Polygons(list(p), "ID")))
if (require(rgeos)) {
stplot(sttdf[pol])
names(sttdf[pol]@traj)
stplot(sttdf[1:2],col=1:2)
stplot(sttdf[,t0])
stplot(sttdf[,"2013"])
stplot(sttdf[pol,"2013"])
is.null(sttdf[pol,t0])
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