Thanks much for the explanations. A few responses below.
On Feb 13, 2010, at 7:25 PM, Glynn Clements wrote: > > Michael Barton wrote: > >> Should r.statistics simply be replaced with r.statistics2? > > You need both r.statistics2 (accumulator-based statistics) and > r.statistics3 (quantiles) to get most of the functionality of > r.statistics. > > Neither module can calculate the mode, although I'm not sure that's > meaningful for FP data (in the absence of quantisation in the original > data, you would expect each value to be unique). > >> No explanation of difference, for example, between kurtosis and kurtosis2. > > The methods whose descriptions begin with "(2-pass)" use a two-pass > algorithm. The first pass calculates the mean, the second pass > calculates the aggregate from the deviations. > > The single-pass algorithms can have very poor accuracy if the standard > deviation is small relative to the mean. You end up calculating: > > (mean^N + a) - (mean^N + b) > > where mean^N swamps a and b, leading to excessive relative error in > the result. > >> It seems that r.statistics3 should be renamed to something more >> descriptive as it differs functionally from r.statistics > > It can be used as a substitute for r.statistics method=median, but can > calculate arbitrary quantiles. It's derived from r.quantile. > > r.statistics relies upon r.stats, which doesn't work with FP data and > which performs poorly with large numbers of categories. So it sounds like r.statistics2 and r.statistics3 are significant improvements over r.statistics. > >> r.external.out and r.colors.out do not generate the GUI when run from >> the command line. > > Both generate a GUI when run with --ui. r.external.out doesn't have > any required arguments (mainly due to -f), while r.colors.out has a > bug: It is unclear how r.external.out works. Does it make a GDAL-compatible file appear as a GRASS raster in a mapset? If so, shouldn't this be r.external.in? (i.e., it makes an external raster usable by GRASS) > >> r.colors.out generates a segmentation fault if run >> without arguments. > > Right; map= should be a required option; fixed in r40984. Thanks. > >> Trying to run ximgview generates the following error: ERROR: >> Incompatible library version for module. You need to rebuild GRASS >> or untangle multiple installations. > > Either it failed to compile and you're trying to run an old version > with a newer library, or the -L flags for wxWidgets caused it to pick > up an old version of the libraries. I compiled after an svn up, followed by make distclean. So I don't know how I could be trying to run an old version. I don't know about the -L flags in wxWidgets. I'm using a Mac where wxWidgets is wrapped in wxPython. > > Also, ximgview should be superseded by wximgview (except, wximgview > currently doesn't build on Windows, for the same reason as xganim and > the vdigit and nviz modules, i.e. trying to link against wxWidgets > crashes "ld"). OK wximgview works. I guess I misunderstood what this did. So it's to offer a way to view graphics created by d.* commands? Michael_______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
