>> >> So, this is the _correct and easy_ way instead of using a couple of | >> (=OR) operators in my case? Or am I misinterpreting it? > > Yes, this is the most direct way to choose the subset of a data.frame > with complete cases - used in lots of places that data.frame objects > are used (since 1992, White Book). Think data.frame objects, not GIS > objects (bands). This is about ontology, really. Yes, or semantics at least.
Currently, a single gridded object in sp (SpatialGridDataFrame or SpatialPixelsDataFrame) holds attributes in the @data slot, and this can be a stack of bands that are spatially alligned, e.g. a set of bands with different spectral characteristics. In addition bands (or variables in the data.frame analogy) can be of different type, e.g. of type logical or factor (think land use type). The bands could also have a different time stamp, representing time series of images, but the sp objects have no infrastructure to capture the time stamp of a band. -- Edzer Pebesma Institute for Geoinformatics (ifgi), University of Münster Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251 8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de/ http://www.springer.com/978-0-387-78170-9 [email protected] _______________________________________________ grass-stats mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-stats
