Filtering by attributes and relations
Now that we know how geometries relate to each other, we can search points using these relations. We already have the means for importing the points and the polygons that represent any kind of boundaries that may be of our interest.
The data that comes with the book files contains examples of world countries' boundaries, but you are free to search the Internet for any data that is significant to you. Remember only that the data coordinates should be in latitudes and longitudes, and they need to have a name field.
For our tests, I prepared a special set of geocaching points that spans the whole globe, and as an exercise, we will filter these points by a country.
The proposed workflow is as follows:
Import the points and boundaries
Find the boundary that we want to use
Filter the points by that boundary
Return the points to the user
To find the points that we want, we will iterate over the data until it hits a match. Iterations can be costly in terms of processing...
