[R-sig-Geo] spacetime: creating STIDF objects

[Facundo Muñoz]

Hi Roland, thanks for your answer.

However, this solution does not work when sp is a SpatialPolygons (which
is my case, of course):

> rbind(sp, sp)

Error in validObject(res) :
  invalid class “SpatialPolygons” object: non-unique Polygons ID slot values


I'm sorry that my toy example didn't reproduce exactly my situation.

Thanks in any case.

ƒacu.-


On 11/09/2017 03:10 PM, Roland Harhoff wrote:
> Hey Facundo,
>
> I'm not sure about the stConstruct issue (yet) ...
> but you can create a STIDF object from your example data by
>
> mystidf <- STIDF(rbind(sp,sp,sp,sp), mydata$time, mydata[ , "values", drop = F])
>
> See also the documentation ...
>
> ?spacetime::STIDF
>
> HTH so far ...!
>
> Best wishes ...
>
> Roland
>
>
> Facundo Muñoz schrieb am 2017-11-09:
>> Dear all, I have just posted an issue [1] in the GitHub repository for
>> the "spacetime" package that I reproduce here:
>> I have a "long" table with irregular data (observations for some
>> municipalities at specific months) that I would like to store together
>> with the administrative map of the region (SpatialPolygons). I tried
>> unsuccessfully to directly create the STIDF object using both
>> `stConstruct()` and `STIDF`.
>> In all the related examples in the package you first create a STFDF
>> which is later coerced to STIDF. But my dataset is very sparse.
>> Here is a reproducible example adapted from the examples in the package.
>> If I use the complete table it leads to a STFDF object as expected and
>> it works fine. However if the table is not complete it should switch to
>> a STIDF representation (as far as I understand from the JSS paper).
>> ``` r
>> library(spacetime)
>> library(sp)
>> sp = cbind(x = c(0,0,1), y = c(0,1,1))
>> row.names(sp) = paste0("point", 1:nrow(sp))
>> sp = SpatialPoints(sp)
>> time = as.POSIXct("2010-08-05")+3600*(10:13)
>> m = c(10,20,30) # means for each of the 3 point locations
>> mydata = rnorm(length(sp)*length(time),mean=rep(m, 4))
>> mydata = data.frame(
>>   space = rep(row.names(sp), 4),
>>   time  = rep(time, each = 3),
>>   values = signif(mydata,3)
>> )
>> mystfdf <- stConstruct(mydata, "space", "time", sp)  # This works OK
>> mystidf <- stConstruct(mydata[-1,], "space", "time", sp)
>> #> Error: nrow(object at time) == length(object at sp) is not TRUE
>> ```
>
>> Thank you in advance.
>> ƒacu.-
>
>> [1] https://github.com/edzer/spacetime/issues/30
>> --
>> Cirad <https://umr-astre.cirad.fr/>
>> *Facundo Muñoz*
>> /Biostatistician/
>> Bios - UMR ASTRE
>> Bureau E-203 - TA A-117 / E
>> Campus international de Baillarguet
>> 34398 Montpellier Cedex 5
>> France
>> +33 467 593 868
>> @famuvie
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo


	[[alternative HTML version deleted]]