Q:

Count Polygons in Buffer using ArcMap? 

I'm using ArcMap and work with a dataset that contains all the buildings of north rhine-westphalia.  This dataset contains different attributes for every object. 
My task is to count all neighboring buildings of a building.  For that I create a buffer (100m) for every building and want count every other building within this buffer.  
How do I do that? 
Additionally, how do I get the mean height of all buildings in this buffer? 

A:

Run Generate Near Table.   Your buildings will be both the input and the near features.   
Join your buildings shapefile to the near table
Summarize the "input features" by the heights of the "near features" 
This should give you a table with the input Feature ID (the ID of the building), the number of other buildings within 100m,  and the average of the elevation of those buildings within 100m.

