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

[Edzer Pebesma]

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/
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>>> Bureau E-203 - TA A-117 / E
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> 
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-- 
Edzer Pebesma
Institute for Geoinformatics
Heisenbergstrasse 2, 48151 Muenster, Germany
Phone: +49 251 8333081