docs and file cleaning

Signed-off-by: Aaron Bu <acb256@cornell.edu>

python/src/main/python/pygw/base_models.py

@@ -246,6 +246,17 @@ def query_statistics(self, q):
         # TODO
         raise NotImplementedError
 
+    """
+    Get a single statistical result that matches the given query criteria
+   
+    Args:
+        q (pygw.special_queries.StatisticsQuery): query the query criteria, use StatisticsQueryBuilder or its extensions and if you're
+           interested in a particular common statistics type use StatisticsQueryBuilder.factory()
+    Returns:
+        If the query does not define that statistics type it will return null as aggregation
+            only makes sense within a single type, otherwise aggregates the results of the query
+            into a single result that is returned
+    """
     def aggregate_statistics(self, q):
         return self._java_ref.aggregateStatistics(q._java_ref)
 

python/src/main/python/pygw/special_queries.py

@@ -2,12 +2,18 @@
 from pygw.base_models import PyGwJavaWrapper, QueryInterface
 
 class StatisticsQuery(QueryInterface):
-  "type is 'bbox' or 'time_range'"
+  """
+  Builds a statistics query for aggregate statistics.
+  To create a StatisticsQuery, for extended_id is the ID of the statisticqs query,
+  and type must either be 'bbox' 'time_range'
+  """
   def __init__(self, extended_id, type):
     if type == "bbox":
       builder = config.MODULE__geotime_query.VectorStatisticsQueryBuilder.newBuilder().factory().bbox()
-    else:
+    elif type == "time_range":
       builder = config.MODULE__geotime_query.VectorStatisticsQueryBuilder.newBuilder().factory().timeRange()
+    else:
+      raise AttributeError("Invalid query type")
 
     builder.fieldName(extended_id)
     java_ref = builder.build()