import.asc imports ESRI ArcInfo ASCII raster file , conversely, export.asc allows to export an asc object to a ESRI ArcInfo ASCII raster file. With Arcview 3.x: ASCII raster files are created using the command ‘File ->, Export data source’ With Arcview 8/9: ASCII raster files are created by the command ‘Arc Toolbox ->, Conversion tools ->, From raster ->, Raster to ASCII’. With GRASS, the best way to import a raster map within R is to use the package spgrass6, and then to use the function spixdf2kasc to convert the files to format that can be managed by adehabitat. ASCII raster files may also be created using other free programs, such as landserf (http://www.soi.city.ac.uk/~jwo/landserf/). Raster maps are stored as matrices of class asc with adehabitat. They may be of type ‘numeric’ (e.g. elevation on an area) or ‘factor’ (e.g. the type of vegetation on an area). If the map is of type factor, the levels should be indicated. The ‘.asc’ files store the values of the mapped variable with numeric values. Each level of the factor is coded on the map by a number. The argument lev of import.asc or as.asc gives the labels corresponding to each number. Alternatively, these levels may be specified using a correspondence table exported from Arcview (with this software, command ‘Theme ->, table’, then ‘File ->, Export’, and finally export in delimited text format). An example of such file is provided in the directory ‘ascfiles’ of the package, see the examples below. export.asc allows only exportation of numeric maps. inside-R.org is a collection of resources about the open-source R Project for the R Statistics Community. This site is sponsored by Revolution Analytics. Source.