Do not use absolute path names for output files. They are raster if
moving window disposition was selected, otherwise they are in
~/.r.li/output folder.
If input raster is not full of null values r.li.padrange returns a
value >=0 that is PADcv.
If input raster is full of null values r.li.padrange returns -1.
If you want to have null values instead run
r.null setnull=-1 map=my_map
after index calculation.
REFERENCES
McGarigal, K., and B. J. Marks. 1995. FRAGSTATS: spatial pattern
analysis program for quantifying landscape structure. USDA For. Serv.
Gen. Tech. Rep. PNW-351.