Hi, I have upgraded r.in.xyz to allow for the following aggregate functions: - skewness - median - percentile - trimmed mean
To make this possible, I created singly linked lists for all points falling into a cell. I followed a suggestion of Glynn and used arrays instead of pointers and stored the head of each list in a raster map ([GRASS-dev] storing pointers in CELL_TYPE maps? (from April 2007)). The linked lists are then used to calculate the corresponding statistics before binning the values. So far we encountered no problems with this approach in our working group, but I'm not sure about some details. Maybe there should be some more checks, e.g. to prevent the index to overflow because of too many cells.
If you are interested I'd like to share the code. Maybe it would be best to send a copy to Hamish first?
Volker _______________________________________________ grass-dev mailing list [email protected] http://grass.itc.it/mailman/listinfo/grass-dev
