spatio-temporal data

That is a good question (I had the same problem when I started using the 
spacetime package). It is all, of course, explained in the spacetime 
package vignette (http://CRAN.R-project.org/package=spacetime), but one 
more time:

To create an object of any class you can always use the command "new" 
(http://stat.ethz.ch/R-manual/R-devel/library/methods/html/new.html). 
For example, to create an object of type STIDF you would use:

new("STIDF", STI(sp, time, endTime), data = data)

But the creators of the spacetime package have also prepared methods 
that would do that for you 
(https://r-forge.r-project.org/scm/viewvc.php/pkg/R/STIDF-methods.R?view=markup&root=spacetime) 
e.g.:

## load the data:
data(HRtemp08)

## format the time column:
HRtemp08$ctime <- as.POSIXct(HRtemp08$DATE, format="%Y-%m-%dT%H:%M:%SZ")

## create a STIDF object:
library(spacetime)
sp <- SpatialPoints(HRtemp08[,c("Lon","Lat")])
proj4string(sp) <- CRS("+proj=longlat +datum=WGS84")
HRtemp08.st <- STIDF(sp, time = HRtemp08$ctime, data = 
HRtemp08[,c("NAME","TEMP")])

See also:

http://plotkml.r-forge.r-project.org/layer.STIDF.html

HTH,

T. Hengl
http://www.wewur.wur.nl/popups/vcard.aspx?id=HENGL001

Dear All,
I want to construct a ST class data with spacetime package.
Observations are cancer mortality rate in 15 fixed locations for
sparse time in 7 years.
I don't know how input my data as a locations and time. I have seen example
data air and fires in this package but I can't understand how they constructed.
for example can I input my data as a below then construct a st class?how?

locations      x      y    time
    point1    cord1   cord2  time1
    point1    cord1   cord2  time2
       .        .       .      .
       .        .       .      .
Best.