[R-sig-Geo] Multiple NAvalue for extract

[Ned Horning]

Hi -

I am trying to extract values from image cells using the raster package 
extract function:
classCellValues <- extract(classImage, classCellNumbers)

The image that I am using has two do-data values that I set using 
NAvalue. When I run extract I get lot of the following warnings:

In if (x at file@nodatavalue < 0) { ... :
   the condition has length > 1 and only the first element will be used

The output from my script seems to be fine but I would like to know if 
there is a problem using multiple values for NAvalue.

I am using raster version 1.9-19 downloaded from the CRAN.

Thanks in advance for any help,

Ned