[R] Problem with adding a raster and a brick

[Michael Sumner]

On Thu, 24 May 2018 at 18:41 Mark R Payne <markpayneatwork using gmail.com> wrote:

Hi,

I seem to be having a problem adding the following two raster objects
together - one is a rasterLayer, the other is a rasterBrick. The extent,
resolution, and origin are the same, so according to my understand it
should work. The objects look like so:

> obs.clim
class : RasterLayer
dimensions : 60, 200, 12000 (nrow, ncol, ncell)
resolution : 0.5, 0.5 (x, y)
extent : -70, 30, 50, 80 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
data source :
/home/mpayne/Documents/Predictability_engine/scratch/Bluefin/HadISST/
obs_climatology.nc
names : sst
z-value : 1988-02-15
zvar : sst

> mdl.anom
class : RasterBrick
dimensions : 60, 200, 12000, 1 (nrow, ncol, ncell, nlayers)
resolution : 0.5, 0.5 (x, y)
extent : -70, 30, 50, 80 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
data source :
/home/mpayne/Documents/Predictability_engine/scratch/Bluefin/DCPP-hindcasts/IPSL-CM5A-LR/B.realmean/IPSL-CM5A-LR_S19610101_L000000_realmean_
anom.nc

names : X1961.08.16
Date : 1961-08-16
varname : tos

When I try to add them together, I get the follow error:

> mdl.val <- obs.clim + mdl.anom
Error in .readRowsNetCDF(x = x, row = row, nrows = nrows, col = col, ncols
= ncols) :
no slot of name "band" for this object of class ".MultipleRasterData"
>

I can reproduce, with netcf-file-backed bricks. I would try

obs.clim[[1]] + mdl.anom[[1]]

or

readAll(obs.clim) + readAll(mdl.anom)

those differ mainly in what will happen to multi-layer versions of the
files, the first will give just the first layer. The key is breaking the
file-read-delay, both objects have no data in memory but the add operation
invalidates and causes read to occur - but with a bug - (I will check in
dev raster and report if necessary).

FYI, R-Sig-Geo is generally a better forum for spatial stuff:
https://stat.ethz.ch/mailman/listinfo/r-sig-geo

Cheers, Mike.


I get the same error if I treat mdl.anom as a raster, or if they are both
bricks. Any suggestions what could be going wrong? Installation details
below

Best wishes,

Mark

> R.version
_
platform x86_64-pc-linux-gnu
arch x86_64
os linux-gnu
system x86_64, linux-gnu
status
major 3
minor 4.2
year 2017
month 09
day 28
svn rev 73368
language R
version.string R version 3.4.2 (2017-09-28)
nickname Short Summer
>
> packageDescription("raster")
Package: raster
Type: Package
Title: Geographic Data Analysis and Modeling
Version: 2.6-7
Date: 2017-11-12

> packageDescription("ncdf4")
Package: ncdf4
Version: 1.16
Date: 2017-04-01

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-- 
Dr. Michael Sumner
Software and Database Engineer
Australian Antarctic Division
203 Channel Highway
Kingston Tasmania 7050 Australia

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