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

[Facundo Muñoz]

Dear Edzer,

thanks for your response. That's cool, but still it does not solve the
problem.

rbind can be useful for a full grid of observations in space-time, but
mine is sparse. So I really need the subset method `[` for
SpatialPolygons, which does not have this argument makeUniqueIDs.

However, you pointed me to the right direction, and from the code of
rbind I could manage to manually perform the subset and building a
replicated spatial object with unique IDs. The code reproducing the
example is in the GitHub issue [1].

In conclusion:

- It would be good to allow for makeUniqueIDs in the method `[`
for the class SpatialPolygons. That would avoid the manual crafting
of the replicated Spatial object

- I think stConstruct() should perform the subsetting internally for
consistency. So that the argument SpatialObj doesn't have a different
meaning dependind of whether x is a full grid or not.

- There is something else going on with |stplot()|, but the object is
correctly created.



[1] https://github.com/edzer/spacetime/issues/30


On 11/09/2017 03:52 PM, Edzer Pebesma wrote:
>
> On 11/09/2017 03:32 PM, Facundo Muñoz wrote:
>> 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
>>
> rbind(sp, sp, makeUniqueIDs = TRUE)
>
>> 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]]
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>