I'm using randomForest in yaImpute to create a yai-type object which associates "L" with landscape features. Then I use the sp() package to impute L to a landscape consisting of four ascii files) I keep getting the message "NA's generated due to illegal level(s)" when I do the imputation. It's probably because one of the landscape features ("as", for aspect/slope) is stored in numeric form but is treated as a factor when the yai object is created. "as" is also stored in numeric form in the ascii grids, of course. I included an "xtypes" argument in the AsciiGridImpute statement, but that did not help. Some relevant statements are: xfiles <- list(DEM_10 = "dem_10.asc", EASTING = "easting.asc", NORTHING = "northing.asc", as = "asp_slop.asc") AsciiGridImpute(yai_ob, xfiles, outfiles, xtypes=list("numeric", "numeric", "integer", "character")) Any insights will be appreciated. I'd particularly like to know how to gain access to the "invisible" list, VALUE, containing unexpectedNA's, illegal levels, and other information that would help me to troubleshoot the issue. Dr. Seth W. Bigelow Biologist, USDA-FS Sierra Nevada Research Center 1731 Research Park Drive, Davis California [[alternative HTML version deleted]]