🩹 Fix issue with single point bounding box

calculation

src/pyinterp/core/lib/geohash/int64.cpp

@@ -304,6 +304,12 @@ auto grid_properties(const geodetic::Box &box, const uint32_t precision)
   auto hash_sw = encode(box.min_corner(), precision);
   auto box_sw = bounding_box(hash_sw, precision);
   auto box_ne = bounding_box(encode(box.max_corner(), precision), precision);
+
+  // Special case: the box is a single point
+  if (box_sw == box_ne) {
+    return std::make_tuple(hash_sw, 1, 1);
+  }
+
   auto lon_offset = box.max_corner().lon() == 180 ? 1 : 0;
   auto lat_offset = box.max_corner().lat() == 90 ? 1 : 0;
 

src/pyinterp/tests/core/test_geohash.py

@@ -5,7 +5,7 @@
 import numpy
 import pytest
 
-from ...core import GeoHash, geohash
+from ...core import GeoHash, geodetic, geohash
 
 testcases = [['77mkh2hcj7mz', -26.015434642, -26.173663656],
              ['wthnssq3w00x', 29.291182895, 118.331595326],
@@ -69,6 +69,14 @@ def test_bounding_boxes():
     with pytest.raises(MemoryError):
         geohash.bounding_boxes(precision=12)
 
+    # Special case: the given polygon represents a single geohash
+    polygon = geodetic.Polygon.read_wkt(
+        'POLYGON((-158.4 -68.4,-158.4 -67.6,-157.6 -67.6,-157.6 -68.4,'
+        '-158.4 -68.4))')
+    bboxes = geohash.bounding_boxes(polygon, precision=3)
+    assert len(bboxes) == 1
+    assert bboxes[0] == b'07z'
+
 
 def test_bounding_zoom():
     bboxes = geohash.bounding_boxes(precision=1)