Added Bindings for Vertex-Related Functions

CHANGELOG.md

@@ -14,9 +14,9 @@ Because H3-Py is versioned in lockstep with the H3 core library, please
 avoid adding features or APIs which do not map onto the
 [H3 core API](https://uber.github.io/h3/#/documentation/api-reference/).
 
-## Unreleased
+## Unreleased - 2024-08-23
 
-- None
+- Added bindings for `cellToVertex`, `cellToVertexes`, `vertexToLatLng`, and `isValidVertex` (#323)
 
 ## [4.0.0b5] - 2024-05-19
 

docs/api_quick.md

@@ -24,6 +24,7 @@ and should be generally aligned with the
    is_pentagon
    is_res_class_III
    is_valid_directed_edge
+   is_valid_vertex
 ```
 
 ## Index representation
@@ -108,6 +109,17 @@ Functions relating H3 objects to geographic (lat/lng) coordinates.
    get_directed_edge_origin
 ```
 
+## Vertexes
+
+```{eval-rst}
+.. currentmodule:: h3
+
+.. autosummary::
+   cell_to_vertex
+   cell_to_vertexes
+   vertex_to_latlng
+```
+
 ## Polygon interface
 
 The ``LatLngPoly`` and ``LatLngMultiPoly`` objects and their related functions allow users to represent (multi)polygons of lat/lng points and convert back and forth between H3 cells.

src/h3/_cy/CMakeLists.txt

@@ -24,6 +24,7 @@ add_cython_file(edges)
 add_cython_file(to_multipoly)
 add_cython_file(error_system)
 add_cython_file(memory)
+add_cython_file(vertex)
 
 
 # Include pyx and pxd files in distribution for use by Cython API
@@ -41,6 +42,8 @@ install(
         error_system.pyx
         memory.pxd
         memory.pyx
+        vertex.pxd
+        vertex.pyx
     DESTINATION
         src/h3/_cy
 )

src/h3/_cy/__init__.py

@@ -60,6 +60,13 @@
     great_circle_distance,
 )
 
+from .vertex import (
+    cell_to_vertex,
+    cell_to_vertexes,
+    vertex_to_latlng,
+    is_valid_vertex,
+)
+
 from .to_multipoly import (
     cells_to_multi_polygon
 )

src/h3/_cy/h3lib.pxd

@@ -69,6 +69,7 @@ cdef extern from 'h3api.h':
     int isPentagon(H3int h) nogil
     int isResClassIII(H3int h) nogil
     int isValidDirectedEdge(H3int edge) nogil
+    int isValidVertex(H3int v) nogil
 
     double degsToRads(double degrees) nogil
     double radsToDegs(double radians) nogil
@@ -80,6 +81,10 @@ cdef extern from 'h3api.h':
     H3Error cellToLatLng(H3int h, LatLng *) nogil
     H3Error gridDistance(H3int h1, H3int h2, int64_t *distance) nogil
 
+    H3Error cellToVertex(H3int cell, int vertexNum, H3int *out) nogil
+    H3Error cellToVertexes(H3int cell, H3int *vertexes) nogil
+    H3Error vertexToLatLng(H3int vertex, LatLng *coord) nogil
+
     H3Error maxGridDiskSize(int k, int64_t *out) nogil # num/out/N?
     H3Error gridDisk(H3int h, int k, H3int *out) nogil
 

src/h3/_cy/latlng.pyx

@@ -8,7 +8,7 @@ from .util cimport (
     check_edge,
     check_res,
     deg2coord,
-    coord2deg,
+    coord2deg
 )
 
 from .error_system cimport check_for_error

src/h3/_cy/util.pxd

@@ -9,4 +9,5 @@ cpdef H3str int_to_str(H3int x)
 cdef check_cell(H3int h)
 cdef check_edge(H3int e)
 cdef check_res(int res)
+cdef check_vertex(H3int v)
 cdef check_distance(int k)

src/h3/_cy/util.pyx

@@ -1,4 +1,4 @@
-from .h3lib cimport H3int, H3str, isValidCell, isValidDirectedEdge
+from .h3lib cimport H3int, H3str, isValidCell, isValidDirectedEdge, isValidVertex
 
 cimport h3lib
 
@@ -7,6 +7,7 @@ from .error_system import (
     H3DomainError,
     H3DirEdgeInvalidError,
     H3CellInvalidError,
+    H3VertexInvalidError
 )
 
 cdef h3lib.LatLng deg2coord(double lat, double lng) nogil:
@@ -73,6 +74,10 @@ cdef check_edge(H3int e):
     if isValidDirectedEdge(e) == 0:
         raise H3DirEdgeInvalidError('Integer is not a valid H3 edge: {}'.format(hex(e)))
 
+cdef check_vertex(H3int v):
+    if isValidVertex(v) == 0:
+        raise H3VertexInvalidError('Integer is not a valid H3 vertex: {}'.format(hex(v)))
+
 cdef check_res(int res):
     if (res < 0) or (res > 15):
         raise H3ResDomainError(res)

src/h3/_cy/vertex.pxd

@@ -0,0 +1,6 @@
+from .h3lib cimport bool, H3int
+
+cpdef H3int cell_to_vertex(H3int h, int vertex_num) except 1
+cpdef H3int[:] cell_to_vertexes(H3int h)
+cpdef (double, double) vertex_to_latlng(H3int v) except *
+cpdef bool is_valid_vertex(H3int v)

src/h3/_cy/vertex.pyx

@@ -0,0 +1,54 @@
+cimport h3lib
+from h3lib cimport bool, H3int
+
+from .util cimport (
+    check_cell,
+    check_vertex,
+    coord2deg
+)
+
+from .error_system cimport check_for_error
+
+from .memory cimport H3MemoryManager
+
+
+cpdef H3int cell_to_vertex(H3int h, int vertex_num) except 1:
+    cdef:
+        H3int out
+
+    check_cell(h)
+
+    check_for_error(
+        h3lib.cellToVertex(h, vertex_num, &out)
+    )
+
+    return out
+
+cpdef H3int[:] cell_to_vertexes(H3int h):
+    cdef:
+        H3int out
+
+    check_cell(h)
+
+    hmm = H3MemoryManager(6)
+    check_for_error(
+        h3lib.cellToVertexes(h, hmm.ptr)
+    )
+    mv = hmm.to_mv()
+
+    return mv
+
+cpdef (double, double) vertex_to_latlng(H3int v) except *:
+    cdef:
+        h3lib.LatLng c
+
+    check_vertex(v)
+
+    check_for_error(
+        h3lib.vertexToLatLng(v, &c)
+    )
+
+    return coord2deg(c)
+
+cpdef bool is_valid_vertex(H3int v):
+    return h3lib.isValidVertex(v) == 1

src/h3/api/basic_int/__init__.py

@@ -996,3 +996,70 @@ def great_circle_distance(latlng1, latlng2, unit='km'):
         lat2, lng2,
         unit = unit
     )
+
+
+def cell_to_vertex(h, vertex_num):
+    """
+    Return a (specified) vertex of an H3 cell.
+
+    Parameters
+    ----------
+    h : H3Cell
+    vertex_num : int
+        Vertex number (0-5)
+
+    Returns
+    -------
+    The vertex
+    """
+    h = _in_scalar(h)
+    h = _cy.cell_to_vertex(h, vertex_num)
+    return _out_scalar(h)
+
+
+def cell_to_vertexes(h):
+    """
+    Return a list of vertexes of an H3 cell.
+    The list will be of length 5 for pentagons and 6 for hexagons.
+
+    Parameters
+    ----------
+    h : H3Cell
+
+    Returns
+    -------
+    A list of vertexes
+    """
+    h = _in_scalar(h)
+    mv = _cy.cell_to_vertexes(h)
+    return _out_collection(mv)
+
+
+def vertex_to_latlng(v):
+    """
+    Return latitude and longitude of a vertex.
+
+    Returns
+    -------
+    lat : float
+        Latitude
+    lng : float
+        Longitude
+    """
+    v = _in_scalar(v)
+    return _cy.vertex_to_latlng(v)
+
+
+def is_valid_vertex(v):
+    """
+    Validates an H3 vertex.
+
+    Returns
+    -------
+    bool
+    """
+    try:
+        v = _in_scalar(v)
+        return _cy.is_valid_vertex(v)
+    except (ValueError, TypeError):
+        return False

tests/test_h3.py

@@ -387,3 +387,58 @@ def test_grid_path_cells():
 
     with pytest.raises(h3.H3ResMismatchError):
         h3.grid_path_cells(h1, '8001fffffffffff')
+
+
+def test_cell_to_vertex():
+    # pentagon
+    assert h3.cell_to_vertex('814c3ffffffffff', 0) == '2014c3ffffffffff'
+    assert h3.cell_to_vertex('814c3ffffffffff', 1) == '2114c3ffffffffff'
+    assert h3.cell_to_vertex('814c3ffffffffff', 2) == '2214c3ffffffffff'
+    assert h3.cell_to_vertex('814c3ffffffffff', 3) == '2314c3ffffffffff'
+    assert h3.cell_to_vertex('814c3ffffffffff', 4) == '2414c3ffffffffff'
+    try:
+        h3.cell_to_vertex('814c3ffffffffff', 5)
+    except h3._cy.error_system.H3DomainError:
+        pass
+    else:
+        assert False
+
+    # hexagon
+    assert h3.cell_to_vertex('814d7ffffffffff', 0) == '2014d7ffffffffff'
+    assert h3.cell_to_vertex('814d7ffffffffff', 1) == '2213abffffffffff'
+    assert h3.cell_to_vertex('814d7ffffffffff', 2) == '2113abffffffffff'
+    assert h3.cell_to_vertex('814d7ffffffffff', 3) == '2414c3ffffffffff'
+    assert h3.cell_to_vertex('814d7ffffffffff', 4) == '2314c3ffffffffff'
+    assert h3.cell_to_vertex('814d7ffffffffff', 5) == '2414cfffffffffff'
+
+
+def test_cell_to_vertexes():
+    # pentagon
+    assert h3.cell_to_vertexes('814c3ffffffffff') == [
+        '2014c3ffffffffff',
+        '2114c3ffffffffff',
+        '2214c3ffffffffff',
+        '2314c3ffffffffff',
+        '2414c3ffffffffff',
+    ]
+
+    # hexagon
+    assert h3.cell_to_vertexes('814d7ffffffffff') == [
+        '2014d7ffffffffff',
+        '2213abffffffffff',
+        '2113abffffffffff',
+        '2414c3ffffffffff',
+        '2314c3ffffffffff',
+        '2414cfffffffffff',
+    ]
+
+
+def test_vertex_to_latlng():
+    latlng = h3.vertex_to_latlng('2114c3ffffffffff')
+    assert latlng == approx((24.945215618732814, -70.33904370008679))
+
+
+def test_is_valid_vertex():
+    assert h3.is_valid_vertex('2114c3ffffffffff')
+    assert not h3.is_valid_vertex(2455495337847029759)
+    assert not h3.is_valid_vertex('foobar')