On Saturday 01 September 2007, Glynn Clements wrote: > Moskovitz, Bob wrote: > > I was just looking at the CVS version of r.neighbors but didn't see > > where I can specify use an arbitrary neighbourhood shape unless it has > > something to do with the weight=string option. Unfortunately the > > documentation doesn't mention how to use it. > > The argument to the weight= option is the name of a file containing > weights. The file should contain NxN floating-point values (anything > acceptable to scanf's %f conversion). > > > So, with r.neighbors, how would I annulus shape neighbourhood shape? > > Create a weights file with a non-zero value for each cell which should > be part of the neighbourhood, and zero elsewhere. E.g. for size=5: > > 0 1 1 1 0 > 1 0 0 0 1 > 1 0 0 0 1 > 1 0 0 0 1 > 0 1 1 1 0 >
This is an excellent update. If this does not make it into the docs soon, let me know and I can cook up some example HTML + images. cheers, Dylan > The minimum, maximum, diversity and interspersion aggregates don't > care about the actual weight; they simply discard any values with a > zero weight and retain those with a non-zero weight. > > For the other aggregates, the way in which the weights affect the > aggregate is fairly intuitive. In particular, an integer weight has > the same effect as repeating the value that may times (integer weights > aren't treated specially; this is just a consequence of how the > weights are handled). > > Finally, note that r.neighbors, r.series and r.resamp.stats all use > use the same code for the aggregates (although r.series only uses the > unweighted forms). -- Dylan Beaudette Soils and Biogeochemistry Graduate Group University of California at Davis 530.754.7341 _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
