Nikos: > > > > What I actually do is nothing but a PCA on a combination of different > > > > bands. The fact is that bands a, b, c are of equal "length" in R and > > > > have _more_ non-NULLs than bands d, e, f.
Dylan: > > > I think that you are going to have to maintain a band-wise null mask in > > > R, as opposed to a single null mask for the entire set of bands. [...] > An idea on how to apply this function: > > # load data > # extract an NA mask using complete.cases > # do something like prcomp() > # assign back to original data > x.df$pca_1[x.na_mask] <- predict(p)[,1] > > This would of course be done the the @data slot on an sp object. Thanks to > Roger for this slick approach. > > How about that!? Very helpful Dylan. I am learning a lot, as usual. However, no-matter what I try to do with my NA's I still get random NA's when I write back to GRASS my data. I tried to load the data, extract an NA_mask using complete.cases, create "fake" columns and fill-in with the _untouched_ original data and then write back to GRASS6. The result (or my process) is _noise_. I'll try again tonight. If I am not going to make it I could try to repeat this with spearfish data and see if something isn't ok with my MODIS bands. Cheers, Nikos I don't understand what's the deal here :-( _______________________________________________ grass-stats mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-stats
