[R-sig-Geo] Error when using rowSums along with a RasterStack object

[Thiago Veloso]

Dear R-colleagues,

I am trying to sum all layers of a RasterStack object, which is summarized below:

> s
class       : RasterStack 
dimensions  : 5568, 8289, 46153152, 46  (nrow, ncol, ncell, nlayers)
resolution  : 0.00898, 0.00898  (x, y)
extent      : -104.4326, -29.99736, -40.00064, 10  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 
min values  : -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, -32768, ... 
max values  : 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, 32767, ... 
layer names : gpp2004001.Gpp_1km, gpp2004009.Gpp_1km, gpp2004017.Gpp_1km, gpp2004025.Gpp_1km, gpp2004033.Gpp_1km, gpp2004041.Gpp_1km, gpp2004049.Gpp_1km, gpp2004057.Gpp_1km, gpp2004065.Gpp_1km, gpp2004073.Gpp_1km, gpp2004081.Gpp_1km, gpp2004089.Gpp_1km, gpp2004097.Gpp_1km, gpp2004105.Gpp_1km, gpp2004113.Gpp_1km, ... 

The raster 's' is composed by 46 satellite images at a resolution of 1km (0.00898degree). Each layer is a 8-day composition of leaf area index and I need to integrate an entire year of LAI. When I try to run the "rowSums" function in this RasterStack, the following error is displayed:

> sos <- rowSums(s,na.rm=FALSE)
Error in rowSums(s, na.rm = FALSE) : 
  'x' must be an array of at least two dimensions

The same occurs when I try to use .rowSums providing matrix dimensions:

> sos <- .rowSums(s,5568,8289)
Error in .rowSums(s, 5568, 8289) : 'x' must be numeric


What am I doing wrong? Is there another way to integrate the layers of a RasterStack object?

Thanks in advance,
Thiago Veloso.

P.S.: Attaching sessionInfo output to provide useful information:

> sessionInfo()
R version 2.15.0 (2012-03-30)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=C                 LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] ncdf_1.6.6    rgdal_0.7-11  raster_1.9-92 sp_0.9-99    

loaded via a namespace (and not attached):
[1] grid_2.15.0    lattice_0.20-6