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How to get the outer boundary of a group of polygons?
In ArcGIS, use the Minimum Bounding Geometry tool. You have several options of which kind of “encompassing” geometry you’d like to get back to clip against. Just remember to use ALL for the group_option parameter if you only want one geometry back.
How to extract coordinates from a polygon in shapely?
Similarly, the CoordinateSequence consisting of the vertices forming the first interior boundary is obtained as polygon.interiors [0].coords, and the list of those vertices (without the repeated point) is obtained as polygon.interiors [0].coords [:-1]. You can use the shapely mapping function:
Is there a way to merge polygons first?
If you need to merge features first, you can run the Dissolve tool. Easiest and quickest way I found is to clip a larger polygon (i.e. a county polygon) with your smaller polygon (i.e. a feature class of a group of voting districts, comprising one magisterial district, in my situation).
How to get the first vertex of a polygon?
To get the first vertex, for example, use polygon.exterior.coords [0]. Note that the first and last points are the same; if you want a list consisting of the vertices without that repeated point, use polygon.exterior.coords [:-1]. You can convert the CoordinateSequence (including the repeated vertex) to a list of points thus:
What are the Rings of a polygon called?
Each ring is a collection of contiguous line segments such that the start point and the end point are the same. The boundary of a polygon is the collection of rings by which the polygon is defined. The boundary contains one or more outer rings and zero or more inner rings.
When to use operatorimportfromjson to create a polygon?
As with the Polygon class methods, when using OperatorImportFromJson to create a polygon the order in which the rings are created doesn’t matter. What matters is the ring orientation. Unlike the Polygon class methods, the start point of each ring must be repeated to specify the end point.