difference — Calculate the difference of two regions.
difference calculates the set-theoretic difference of two regions:
(Regions in Region) - (Regions in Sub)
The resulting region is defined as the input region (Region) with all points from Sub removed. Note that, internally, all regions of Sub are united to a single region before the differences between the individual regions of Region and the united region are calculated.
Empty regions are valid for both parameters. On output, empty regions may result. The value of the system flag 'store_empty_region' determines the behavior in this case.
Regions to be processed.
The union of these regions is subtracted from Region.
* provides the region X without the points in Y difference(X,Y,RegionDifference)
Let N be the number of regions, F_1 be their average area, and F_2 be the total area of all regions in Sub. Then the runtime complexity is O(F_1 * log(F_1) + N * (sqrt(F_1) + sqrt(F_2))).
difference always returns the value 2 (H_MSG_TRUE). The behavior in case of empty input (no regions given) can be set via set_system('no_object_result',<Result>) and the behavior in case of an empty input region via set_system('empty_region_result',<Result>). If necessary, an exception is raised.
threshold, connection, regiongrowing, pouring, class_ndim_norm
intersection, union1, union2, complement, symm_difference