How to perform 2 Proportionoverlap queries in MapInfo Pro
UPDATED: August 22, 2017
A large polygon covers portions of multiple States
Note: the order of the tables is crucial in these types of queries.
The 1st table listed in the Proportionoverlap function is the table being overlapped.
The query returns what percentage of those objects being overlapped, are overlapped by the 2nd table.
The 2nd table listed in the Proportionoverlap function is the table doing the overlapping
1) To find the percentage of each region (i.e.State, etc.) covered by a polygon:
Note how Nevada and Utah have a value of 100 (%). This is because the Proportionovelap returned a value of "1" for those 2 objects, which means the object was completely covered - the query returned "100" because the "Select Columns" section had a multiplier to return percentage (* 100 )
2) To find what percentage of the POLYGON covers each State:
ProportionOverlap ( object1, object2 )
object1 is the bottom object (not text or points), i.e. the object whose proportion of overlap is being calculated.
object2 is the top object (not text or points), i.e. the object that does the overlapping.
** The order in which the objects are listed is critical. If the order is switched, a different value will be returned.**
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