test_polygon.py

"""Polygons and Linear Rings
"""
from . import unittest, numpy
from shapely.wkb import loads as load_wkb
from shapely.geos import lgeos
from shapely.geometry import Point, Polygon, asPolygon
from shapely.geometry.polygon import LinearRing, LineString, asLinearRing
from shapely.geometry.base import dump_coords


class PolygonTestCase(unittest.TestCase):

    def test_polygon(self):

        # Initialization
        # Linear rings won't usually be created by users, but by polygons
        coords = ((0.0, 0.0), (0.0, 1.0), (1.0, 1.0), (1.0, 0.0))
        ring = LinearRing(coords)
        self.assertEqual(len(ring.coords), 5)
        self.assertEqual(ring.coords[0], ring.coords[4])
        self.assertEqual(ring.coords[0], ring.coords[-1])
        self.assertTrue(ring.is_ring)

        # Coordinate modification
        ring.coords = ((0.0, 0.0), (0.0, 2.0), (2.0, 2.0), (2.0, 0.0))
        self.assertEqual(
            ring.__geo_interface__,
            {'type': 'LinearRing',
             'coordinates': ((0.0, 0.0), (0.0, 2.0), (2.0, 2.0), (2.0, 0.0),
                             (0.0, 0.0))})

        # Test ring adapter
        coords = [[0.0, 0.0], [0.0, 1.0], [1.0, 1.0], [1.0, 0.0]]
        ra = asLinearRing(coords)
        self.assertTrue(ra.wkt.upper().startswith('LINEARRING'))
        self.assertEqual(dump_coords(ra),
                         [(0.0, 0.0), (0.0, 1.0), (1.0, 1.0), (1.0, 0.0),
                          (0.0, 0.0)])
        coords[3] = [2.0, -1.0]
        self.assertEqual(dump_coords(ra),
                         [(0.0, 0.0), (0.0, 1.0), (1.0, 1.0), (2.0, -1.0),
                          (0.0, 0.0)])

        # Construct a polygon, exterior ring only
        polygon = Polygon(coords)
        self.assertEqual(len(polygon.exterior.coords), 5)

        # Ring Access
        self.assertIsInstance(polygon.exterior, LinearRing)
        ring = polygon.exterior
        self.assertEqual(len(ring.coords), 5)
        self.assertEqual(ring.coords[0], ring.coords[4])
        self.assertEqual(ring.coords[0], (0., 0.))
        self.assertTrue(ring.is_ring)
        self.assertEqual(len(polygon.interiors), 0)

        # Create a new polygon from WKB
        data = polygon.wkb
        polygon = None
        ring = None
        polygon = load_wkb(data)
        ring = polygon.exterior
        self.assertEqual(len(ring.coords), 5)
        self.assertEqual(ring.coords[0], ring.coords[4])
        self.assertEqual(ring.coords[0], (0., 0.))
        self.assertTrue(ring.is_ring)
        polygon = None

        # Interior rings (holes)
        polygon = Polygon(coords, [((0.25, 0.25), (0.25, 0.5),
                                    (0.5, 0.5), (0.5, 0.25))])
        self.assertEqual(len(polygon.exterior.coords), 5)
        self.assertEqual(len(polygon.interiors[0].coords), 5)
        with self.assertRaises(IndexError):  # index out of range
            polygon.interiors[1]

        # Test from another Polygon
        copy = Polygon(polygon)
        self.assertEqual(len(polygon.exterior.coords), 5)
        self.assertEqual(len(polygon.interiors[0].coords), 5)
        with self.assertRaises(IndexError):  # index out of range
            polygon.interiors[1]

        # Coordinate getters and setters raise exceptions
        self.assertRaises(NotImplementedError, polygon._get_coords)
        with self.assertRaises(NotImplementedError):
            polygon.coords

        # Geo interface
        self.assertEqual(
            polygon.__geo_interface__,
            {'type': 'Polygon',
             'coordinates': (((0.0, 0.0), (0.0, 1.0), (1.0, 1.0), (2.0, -1.0),
                             (0.0, 0.0)), ((0.25, 0.25), (0.25, 0.5),
                             (0.5, 0.5), (0.5, 0.25), (0.25, 0.25)))})

        # Adapter
        hole_coords = [((0.25, 0.25), (0.25, 0.5), (0.5, 0.5), (0.5, 0.25))]
        pa = asPolygon(coords, hole_coords)
        self.assertEqual(len(pa.exterior.coords), 5)
        self.assertEqual(len(pa.interiors), 1)
        self.assertEqual(len(pa.interiors[0].coords), 5)

        # Test Non-operability of Null rings
        r_null = LinearRing()
        self.assertEqual(r_null.wkt, 'GEOMETRYCOLLECTION EMPTY')
        self.assertEqual(r_null.length, 0.0)

        # Check that we can set coordinates of a null geometry
        r_null.coords = [(0, 0), (1, 1), (1, 0)]
        self.assertAlmostEqual(r_null.length, 3.414213562373095)

        # Error handling
        with self.assertRaises(ValueError):
            # A LinearRing must have at least 3 coordinate tuples
            Polygon([[1, 2], [2, 3]])


    def test_linearring_from_closed_linestring(self):
        coords = [(0.0, 0.0), (1.0, 0.0), (1.0, 1.0), (0.0, 0.0)]
        line = LineString(coords)
        ring = LinearRing(line)
        self.assertEqual(len(ring.coords), 4)
        self.assertEqual(ring.coords[:], coords)
        self.assertEqual('LinearRing',
                         lgeos.GEOSGeomType(ring._geom).decode('ascii'))


    def test_linearring_from_unclosed_linestring(self):
        coords = [(0.0, 0.0), (1.0, 0.0), (1.0, 1.0), (0.0, 0.0)]
        line = LineString(coords[:-1])  # Pass in unclosed line
        ring = LinearRing(line)
        self.assertEqual(len(ring.coords), 4)
        self.assertEqual(ring.coords[:], coords)
        self.assertEqual('LinearRing',
                         lgeos.GEOSGeomType(ring._geom).decode('ascii'))


    @unittest.skipIf(not numpy, 'Numpy required')
    def test_numpy(self):

        from numpy import array, asarray
        from numpy.testing import assert_array_equal

        a = asarray(((0., 0.), (0., 1.), (1., 1.), (1., 0.), (0., 0.)))
        polygon = Polygon(a)
        self.assertEqual(len(polygon.exterior.coords), 5)
        self.assertEqual(dump_coords(polygon.exterior),
                         [(0., 0.), (0., 1.), (1., 1.), (1., 0.), (0., 0.)])
        self.assertEqual(len(polygon.interiors), 0)
        b = asarray(polygon.exterior)
        self.assertEqual(b.shape, (5, 2))
        assert_array_equal(
            b, array([(0., 0.), (0., 1.), (1., 1.), (1., 0.), (0., 0.)]))

    def test_dimensions(self):

        # Background: see http://trac.gispython.org/lab/ticket/168
    # http://lists.gispython.org/pipermail/community/2008-August/001859.html

        coords = ((0.0, 0.0, 0.0), (0.0, 1.0, 0.0), (1.0, 1.0, 0.0),
                  (1.0, 0.0, 0.0))
        polygon = Polygon(coords)
        self.assertEqual(polygon._ndim, 3)
        gi = polygon.__geo_interface__
        self.assertEqual(
            gi['coordinates'],
            (((0.0, 0.0, 0.0), (0.0, 1.0, 0.0), (1.0, 1.0, 0.0),
              (1.0, 0.0, 0.0), (0.0, 0.0, 0.0)),))

        e = polygon.exterior
        self.assertEqual(e._ndim, 3)
        gi = e.__geo_interface__
        self.assertEqual(
            gi['coordinates'],
            ((0.0, 0.0, 0.0), (0.0, 1.0, 0.0), (1.0, 1.0, 0.0),
             (1.0, 0.0, 0.0), (0.0, 0.0, 0.0)))

    def test_attribute_chains(self):

        # Attribute Chaining
        # See also ticket #151.
        p = Polygon(((0.0, 0.0), (0.0, 1.0), (-1.0, 1.0), (-1.0, 0.0)))
        self.assertEqual(
            list(p.boundary.coords),
            [(0.0, 0.0), (0.0, 1.0), (-1.0, 1.0), (-1.0, 0.0), (0.0, 0.0)])

        ec = list(Point(0.0, 0.0).buffer(1.0, 1).exterior.coords)
        self.assertIsInstance(ec, list)  # TODO: this is a poor test

        # Test chained access to interiors
        p = Polygon(
            ((0.0, 0.0), (0.0, 1.0), (-1.0, 1.0), (-1.0, 0.0)),
            [((-0.25, 0.25), (-0.25, 0.75), (-0.75, 0.75), (-0.75, 0.25))]
        )
        self.assertEqual(p.area, 0.75)

        """Not so much testing the exact values here, which are the
        responsibility of the geometry engine (GEOS), but that we can get
        chain functions and properties using anonymous references.
        """
        self.assertEqual(
            list(p.interiors[0].coords),
            [(-0.25, 0.25), (-0.25, 0.75), (-0.75, 0.75), (-0.75, 0.25),
             (-0.25, 0.25)])
        xy = list(p.interiors[0].buffer(1).exterior.coords)[0]
        self.assertEqual(len(xy), 2)

        # Test multiple operators, boundary of a buffer
        ec = list(p.buffer(1).boundary.coords)
        self.assertIsInstance(ec, list)  # TODO: this is a poor test


def test_suite():
    return unittest.TestLoader().loadTestsFromTestCase(PolygonTestCase)