[R-sig-Geo] Overlaying time designated spatial points from a data frame to match the time of a raster image in a rasterStack

[Frede Aakmann Tøgersen]

Hi

Is it something like this you want to have?


library(raster)
library(latticeExtra)

f <- system.file("external/test.grd", package="raster")

d <- seq(as.Date("2010-01-01"),as.Date("2014-08-01"),by="month")

rr <- stack(rep(f,length(d)))
names(rr) <- d

rr <- setZ(rr, d, name = 'Month')

rr.mean <- zApply(rr, by = function(x)format(x, '%m'), fun = mean, name = "Month")
names(rr.mean) <- month.abb

### For each date sample 10 points from the rasterbrick
pdat <- NULL
for (i in 1:length(d)){
    cells <- sample(1:ncell(rr[[1]]), 10)
    xy <- xyFromCell(rr, cells)
    tmp <- data.frame(x = xy[,"x"], y = xy[, "y"], Month = format(d[i], '%m'), CellId = cells)
    pdat <- rbind(pdat, tmp)
}

levelplot(rr.mean) + xyplot(y ~ x|Month, data = pdat, pch = 13, col = "black")

Yours sincerely / Med venlig hilsen


Frede Aakmann Tøgersen
Specialist, M.Sc., Ph.D.
Plant Performance & Modeling

Technology & Service Solutions
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> -----Original Message-----
> From: r-sig-geo-bounces at r-project.org [mailto:r-sig-geo-bounces at r-
> project.org] On Behalf Of Navinder Singh
> Sent: 22. oktober 2014 23:57
> To: r-sig-geo at r-project.org
> Cc: oscar.perpinan at upm.es
> Subject: [R-sig-Geo] Overlaying time designated spatial points from a data
> frame to match the time of a raster image in a rasterStack
> 
> Hi,
> 
> I have a level plot with a number of rasters (monthly rasters for a year-
> generated with kind help from Oscar). Basically a raster stack.
> 
> I would like to overlay spatial points on this raster stack, but would like to
> overlay only those points that belong to the month matching the raster stack.
> For e.g. The points form January should fall on the raster from January, those
> from february should fall on February raster as so on. I am drowning in the
> �lattice' literature but have not succeeded till now.
> 
> I am running the following code but not sure how to assign an index which
> can delegate the points from respective months to their rasters in the layer +
> sp. points argument from rasterVis package.
> 
> My data frame has the following columns:
> df= X, Y, date (POSIXct), month (month.abb), id (animalID), SITE (a factor
> with origin area)
> 
> The rasters also have names in the format of month.abb.
> 
> And the code i am using is:
> 
> rrMean is a raster stack of monthly means. dfSp is a SpatialPointDataFrame
> with above fields.
> 
> p<-levelplot(rrMean, main="Mean Monthly NDVI (2010-2014)",
> par.settings=myTheme)
> p+layer(sp.points(dfSp,col=dfSp$SITE))
> 
> # I understand that col argument just changes the colours but still plots all
> points on all rasters, but i guess i need something specified
> in sp.points(dfSp,col=dfSp$SITE).
> 
> Thanks for any suggestions.
> 
> Best wishes,
> 
> Navinder
> email: navinder.singh at slu.se<mailto:navinder.singh at slu.se>
> 
> 
> 
> 
> 
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