Convert polyline with Left ID and Right ID to polygons with ID

Question

I have a polyline shape file which contain Left Id and Right ID information and struggling in converting this polyline layer to polygon with ID via arcpy.

I am using ArcGIS(editor) license so feature to polygon tool is not available to me. I also know there are number of methods available like this and this one in ArcGIS if you have editor license but i want to use arcpy to automate my workflow.

Any ideas how i can do it using arcpy?

Answer 1

I don't see a strightforward way of doing this in ArcPy normal licensing without re-inventing wheels..

Just read about Shapely (download link),a python package, which includes the "polygonize" function from familiar JTS/GEOS suites..

My idea is that we can import the Shapely package in ArcPy and get the WKT of the ESRI polyline geometries and pass them to the polygonizer. This will give the resulting polygons. These could be converted back to ESRI polyline geometries. Although i should say, my Python knowledge is terrible..this is just a generic idea..

here is a sample of polygonizer..

>>> from shapely.geometry import LineString, Point
    >>> from shapely.ops import polygonize
    >>> lines = [
    ... LineString(((0, 0), (1, 1))),
    ... LineString(((0, 0), (0, 1))),
    ... LineString(((0, 1), (1, 1))),
    ... LineString(((1, 1), (1, 0))),
    ... LineString(((1, 0), (0, 0))),
    ... LineString(((5, 5), (6, 6))),
    ... Point(0, 0),
    ... ]
    >>> result = polygonize(lines)
    >>> list(result)
    [<shapely.geometry.polygon.Polygon object at ...>, <shapely.geometry.polygon.Polygon object at ...>]

    >>> lines2 = [
    ... ((0, 0), (1, 1)),
    ... ((0, 0), (0, 1)),
    ... ((0, 1), (1, 1)),
    ... ((1, 1), (1, 0)),
    ... ((1, 0), (0, 0)),
    ... ((5, 5), (6, 6)),
    ... ]
    >>> result2 = polygonize(lines2)
    >>> list(result2)
    [<shapely.geometry.polygon.Polygon object at ...>, <shapely.geometry.polygon.Polygon object at ...>]

Also i am not sure what we can do with the LEFT_ID and RIGHT_ID. I think these are irrelevant. Update me if i am wrong.

Answer 2

maybe you could use arcpy.FeatureToRaster_conversion() to create a raster from you polylines and then arcpy.RasterToPolygon_conversion() to create the polygon

Answer 3

If you want to use Python and the GeoProcessor to build polygons from you lines you need to have a look at the Help file and search for a page called working with geometry in Python.

You'll need to create a cursor over your polylines and string them together, you may need to "explode" them into points first? Anyway not sure how you can resolve the issue of the order you visit the polylines. I don't know (as I've never tried it in Python) if the resulting polygon geometry can be simplified, i.e. the order of vertices is made correct when you create the polygon.