# Matching points in table to polygons

this is my first post to this forum. I hope to start participating actively.

I have a table with several records (aprox 200.000), each with its own coordinates. And I need to identify the "Polygon" where each point belongs (I got another table with the vertex for earch polygon) . I am working with Excel and Access at this point. Thanks for the help!

(the polygons doesn’t have holes and doesn’t overlap with other polygon)

I know there is an algorithm that checks if the number of times a line cross another line from the desired point to another point is even, the point is inside polygon, if the number is odd, the point is outside the polygon. But I don’t know how to implement this. Here are some reference links with the algorithm:

http://alienryderflex.com/polygon/

Here is a sample:

I got a table similar to this:

• Point_ID / Coordinates
• 1 / -70.559349,-33.411913
• 2 / -70.579004,-33.407542
• etc. (aprox. 200.000 points)

And I got the following table defining the boundaries of each polygon:

• Polygon_ID / Polygon_Sequence / Coordinates
• 1 / 1 / -70.567331,-33.408803
• 1 / 2 / -70.584755,-33.414249
• 1 / 3 / -70.586987,-33.409692
• 1 / 4 / -70.585527,-33.404175
• 1 / 5 / -70.571537,-33.398084
• 1 / 6 / -70.567331,-33.408803
• 2 / 1 / -70.567245,-33.409047
• 2 / 2 / -70.564756,-33.416570
• 2 / 3 / -70.552998,-33.418576
• 2 / 4 / -70.551796,-33.408474
• 2 / 5 / -70.560122,-33.407542
• 2 / 6 / -70.562525,-33.407327
• 2 / 7 / -70.567245,-33.409047
• etc...

So, this is the output I need (in bold):

• Point_ID / Coordinates / Polygon_ID
• 1 / -70.559349,-33.411913 / 2
• 2 / -70.579004,-33.407542 / 1
• etc...

Thanks a lot! Alejandro

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