An update, I have been able to automate the MannKendall test and capture the
output into a .txt file:
lat<-seq(-125,-67,0.5)
lon<-seq(25,53,0.5)
fun.mk<-function(x){
for (i in 1:length(lat)){
for (j in 1:length(lon)){
v<-rev(extract(x,SpatialPoints(cbind(lat[i],lon[j]))))
mk<-MannKendall(v)
pv<-mk$sl
out<-data.frame(cbind(lat[i],lon[j],pv[1]))
write.table(out,"myraster.mk.txt",append=TRUE,col.names=FALSE,row.names=FALSE,quote=FALSE)
}}}
myraster.mk<-fun.mk(myraster)
Now, I would like to read that file back into R as a RasterLayer. So far, I can
read it in as a table to get:
myraster.table<-read.table("myraster.mk.txt",header=FALSE)
myraster.table
V1 V2 V3
1 -86.000 35.000 0.071539655
2 -86.000 35.125 0.004216323
3 -86.000 35.250 0.449751556
4 -86.000 35.375 0.124644011
5 -86.000 35.500 0.128179774
In the Raster package, there is "as.data.frame" to go from raster->data.frame
but I can't find anything to go in the opposite direction, data.frame->raster.
I tried using "as.raster", but that didn't work:
myraster.raster<-as.raster(myraster.table)
Error in UseMethod("as.raster") :
no applicable method for 'as.raster' applied to an object of class
"data.frame"
Thanks,
Tiffany
On Aug 1, 2012, at 6:24 PM, Tiffany Smith wrote:
> Hello,
>
> I'm trying to do a Mann-Kendall test on my RasterBrick data. So far, I've
> been able to complete the Mann-Kendall test (via the "Kendall" package) by
> extracting a series like so:
>
> onelocation<-rev(extract(myraster,SpatialPoints(cbind(-86,33))))
> onelocation.mk<-MannKendall(onelocation)
>
> I need help either figuring out a way to do the MK test with raster data, or
> if I loop through all points and use the above commands, how can I return
> that data into a Raster so I can visualize the results by making maps?
>
> Thanks,
> Tiffany
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