spRbind for spplot

Hi Klaus,

When I try

plot_poly = rtopObj3$observations
plot_poly$predictions = rtopObj3$predictions$var1.pred
spplot(plot_poly, c("observations", "predictions"))

it does not work since the replacement has 2100 rows and the data has 
100.

I would like to create a new object (e.g. plot_poly) which holds the 
spatial information of all catchment-polygons (nor) as well as the 
attributes of both observations$QNORM_12_4 and predictions$var1.pred 
to the corresponding areas. Therefore, I thought spRbind might be a 
propper solution.

Following up on Pauls suggestion, I think the best is first to make sure 
that you have the same column names in both objects:

observations$var1.pred = NA
predictions$QNORM_12_4 = NA
obs = observations[,c("QNORM_12_4","var1.pred")]
pred = predictions[,c("QNORM_12_4","var1.pred")]
# Now both objects should just contain columns for observations and 
predictions

Then you most likely have to make sure that you have different polygon 
IDs in the two objects. You can try without first, but will most likely 
get an error. If the following does not work, try a larger number:
pred = spChFIDs(pred,as.character(1000+c(1:dim(pred)[1])))

You can then combine the objects:
plot_poly = spRbind(obs,pred)

spplot(plot_poly,c("QNORM_12_4","var1.pred"))

Hope this works!
Jon