[R-sig-Geo] no slot of name "data" for this object of class "RasterStack"

[Peter B. Pearman]

Dear All,

I would, as a complete novice with raster() and associated R, very much 
appreciate any helpful suggestion here.

I created an xy-file and a stack of cropped rasters. The cropping was 
done the xy-file is the same size as the rasters (and stack), i.e. I'm 
trying to sample all the pixels.  But when I try to extract the values 
for all pixels of the rasters in the stack, I get the following error 
message:

 > full.area <- extract(raster.stack,xyfile)
Error in .readCells(x at layers[[j]], cells) :
   no slot of name "data" for this object of class "RasterStack"

I would greatly appreciate any constructive comment.

Best,

Peter


#The following is most of the code to create the raster stack and sample 
it using extract(), but which instead creates the error message.
library(rgdal)
library(raster)
library(utils)

dir.string <- "../WC_10min/"
vargroup <- c("bio","prec","tmax","tmin","tmean")
numfiles <- c(19,12,12,12,12)

mask <- raster("wheatmask")
extent <- extent(mask)

xmin <- attributes(extent)$xmin
xmax <- attributes(extent)$xmax
ymin <- attributes(extent)$ymin
ymax <- attributes(extent)$ymax
xlength <- dim(mask)[2]
ylength <- dim(mask)[1]


# make a file with coordinates for the mask area
x <- seq(from=xmin, to=xmax, length.out=xlength)
y <- seq(from=ymin,to=ymax,length.out=ylength)
xyfile <- expand.grid(x,y)

...

# create the raster stack
raster.stack <- stack()

# fill the stack with cropped climate rasters
raster.name.index <- 0
for (i in 1:length(numfiles)) {
   counter <- numfiles[i]
   for(j in 1:counter) {
     raster.name.index <- raster.name.index + 1
     rasterfile <- 
paste("../WC_10min/",vargroup[i],"/",vargroup[i],"_",j,sep="")
     eval(parse(text=paste(raw.raster.names[raster.name.index],".raw <- 
raster('",rasterfile,"')",sep="")))
     eval(parse(text=paste(raw.raster.names[raster.name.index],"<- 
crop(",raw.raster.names[raster.name.index],".raw,extent)",sep="")))
     eval(parse(text=paste("raster.stack <- 
stack(raster.stack,",raw.raster.names[raster.name.index],")",sep="")))
     print(paste("stack size is now ",raster.name.index,sep=""))
   }
}
full.area <- extract(raster.stack,xyfile)

Here is some more info on the objects:

 > head(xyfile)
       long      lat
1 5.745968 1.982493
2 5.912968 1.982493
3 6.079968 1.982493
4 6.246968 1.982493
5 6.413968 1.982493
6 6.580968 1.982493

# here is a partial attributes listing of the stack
 > attributes(raster.stack)
$filename
[1] ""

$layers
$layers[[1]]
class       : RasterStack
dimensions  : 418, 501, 1  (nrow, ncol, nlayers)
ncell       : 209418
projection  : +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs 
+towgs84=0,0,0
min values  : -132
max values  : 314
extent      : 5.666676, 89.16668, 2.000003, 71.66667  (xmin, xmax, ymin, 
ymax)
resolution  : 0.1666667, 0.1666667  (x, y)


$layers[[2]]
class       : RasterLayer
filename    :
dimensions  : 418, 501, 1  (nrow, ncol, nlayers)
ncell       : 209418
min value   : 38
max value   : 204
projection  : +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs 
+towgs84=0,0,0
extent      : 5.666676, 89.16668, 2.000003, 71.66667  (xmin, xmax, ymin, 
ymax)
resolution  : 0.1666667, 0.1666667  (x, y)


$layers[[3]]
class       : RasterLayer
filename    :
dimensions  : 418, 501, 1  (nrow, ncol, nlayers)
ncell       : 209418
min value   : 16
max value   : 88
projection  : +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs 
+towgs84=0,0,0
extent      : 5.666676, 89.16668, 2.000003, 71.66667  (xmin, xmax, ymin, 
ymax)
resolution  : 0.1666667, 0.1666667  (x, y)

...

I note that the first entry (above) is of class 'RasterStack', not 
'RasterLayer'.  Could this be important?