Reintroduce shared_paths (#77)

pygeos/linear.py

@@ -1,7 +1,7 @@
 from . import lib
 from . import Geometry  # NOQA
 
-__all__ = ["line_interpolate_point", "line_locate_point", "line_merge"]
+__all__ = ["line_interpolate_point", "line_locate_point", "line_merge", "shared_paths"]
 
 
 def line_interpolate_point(line, distance, normalize=False):
@@ -87,3 +87,28 @@ def line_merge(line):
     <pygeos.Geometry GEOMETRYCOLLECTION EMPTY>
     """
     return lib.line_merge(line)
+
+
+def shared_paths(geom1, geom2):
+    """Returns the shared paths between geom1 and geom2.
+
+    Both geometries should be linestrings or arrays of linestrings.
+    A geometrycollection or array of geometrycollections is returned
+    with each geometrycollection two elements. The first element is a
+    multilinestring containing shared paths with the same direction
+    for both inputs. The second element is a multilinestring containing
+    shared paths with the opposite direction for the two inputs.
+
+    Parameters
+    ----------
+    geom1 : Geometry or array_like
+    geom2 : Geometry or array_like
+
+    Examples
+    --------
+    >>> geom1 = Geometry("LINESTRING (0 0, 1 0, 1 1, 0 1, 0 0)")
+    >>> geom2 = Geometry("LINESTRING (1 0, 2 0, 2 1, 1 1, 1 0)")
+    >>> shared_paths(geom1, geom2)
+    <pygeos.Geometry GEOMETRYCOLLECTION (MULTILINESTRING EMPTY, MULTILINESTRING ((1 0, 1 1)))>
+    """
+    return lib.shared_paths(geom1, geom2)

pygeos/test/test_linear.py

@@ -64,3 +64,16 @@ def test_line_merge_geom_array():
     actual = pygeos.line_merge([line_string, multi_line_string])
     assert pygeos.equals(actual[0], line_string)
     assert pygeos.equals(actual[1], multi_line_string)
+
+
+def test_shared_paths_linestring():
+    g1 = pygeos.linestrings([(0, 0), (1, 0), (1, 1)])
+    g2 = pygeos.linestrings([(0, 0), (1, 0)])
+    actual1 = pygeos.shared_paths(g1, g2)
+    assert pygeos.equals(pygeos.get_geometry(actual1, 0), g2)
+
+
+def test_shared_paths_none():
+    assert pygeos.shared_paths(line_string, None) is None
+    assert pygeos.shared_paths(None, line_string) is None
+    assert pygeos.shared_paths(None, None) is None

src/ufuncs.c

@@ -391,6 +391,7 @@ static void *intersection_data[1] = {GEOSIntersection_r};
 static void *difference_data[1] = {GEOSDifference_r};
 static void *symmetric_difference_data[1] = {GEOSSymDifference_r};
 static void *union_data[1] = {GEOSUnion_r};
+static void *shared_paths_data[1] = {GEOSSharedPaths_r};
 typedef void *FuncGEOS_YY_Y(void *context, void *a, void *b);
 static char YY_Y_dtypes[3] = {NPY_OBJECT, NPY_OBJECT, NPY_OBJECT};
 static void YY_Y_func(char **args, npy_intp *dimensions,
@@ -1399,6 +1400,7 @@ int init_ufuncs(PyObject *m, PyObject *d)
     DEFINE_YY_Y (difference);
     DEFINE_YY_Y (symmetric_difference);
     DEFINE_YY_Y (union);
+    DEFINE_YY_Y (shared_paths);
 
     DEFINE_Y_d (get_x);
     DEFINE_Y_d (get_y);