Q: Now I have the road network data and the residential community point data for a certain area. How can I pick some candidate locations for building some shopping malls with at least three residential points within 2km?

A: (1) You can use the service area analysis in the network analysis. Select residential points as service points, set service radius to 2 km, and you can find the result in a CAD dataset of a temporary datasource. You can copy the result dataset and convert it into a simple region dataset.

 (2) Finally, you can find areas with more than 3 overlaps through topology checking. Those areas can serve as the candidate areas for shopping malls. For topology checking, you can firstly perform the topological checking with the condition No overlap within region on the simple region dataset obtained from last step. Then, perform the same topological checking again on the result of the first topological checking operation. Finally, perform the topological checking with the same condition again on the result of the second topological checking operation to get areas satisfying the conditions required.