fix: support non float 64 longitudes and latitudes

this was working before numpy 2.0 since the conversion was done without us knowing

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+### Fixed
+
+* support longitudes and latitudes that are not of `dtype` `np.float64`. This was broken
+  by numpy 2.0. Before that, the conversion was done silently. See [#35]
+
 ## 0.7.1
 
 ### Added

python/cdshealpix/tests/test_nested_healpix.py

@@ -31,7 +31,7 @@
 )
 
 
-@pytest.mark.parametrize("size", [1, 10, 100, 1000, 10000, 100000])
+@pytest.mark.parametrize("size", [1, 10, 100])
 def test_lonlat_to_healpix(size):
     depth = np.random.randint(30)
     lon = Longitude(np.random.rand(size) * 360, u.deg)
@@ -52,7 +52,18 @@ def test_lonlat_to_healpix(size):
     assert ((dy >= 0) & (dy <= 1)).all()
 
 
-@pytest.mark.parametrize("size", [1, 10, 100, 1000, 10000, 100000])
+# regression test for issue #35
+def test_lonlat_to_healpix_float32():
+    healpix = lonlat_to_healpix(
+        lon=Longitude(np.array(3, dtype=np.float32), "deg"),
+        lat=Latitude(np.array(5, dtype=np.float32), "deg"),
+        depth=2,
+    )
+    assert len(healpix) == 1
+    assert healpix[0] == 76
+
+
+@pytest.mark.parametrize("size", [1, 10, 100])
 def test_healpix_to_lonlat(size):
     depth = np.random.randint(30)
     ipixels = np.random.randint(12 * 4**depth, size=size, dtype=np.uint64)

python/cdshealpix/utils.py

@@ -6,7 +6,7 @@
 
 from . import cdshealpix
 
-__all__ = ["to_ring", "from_ring"]
+__all__ = ["from_ring", "to_ring"]
 
 # Raise a ValueError exception if the input
 # HEALPix cells array contains invalid values
@@ -42,8 +42,16 @@ def _validate_lonlat_wrap(lon, lat, *args, **kwargs):
                 f"'lon' and 'lat' should have the same shape but are of shapes {lon.shape} and {lat.shape}",
             )
         # convert into astropy objects
-        lon = lon if isinstance(lon, Longitude) else Longitude(lon)
-        lat = lat if isinstance(lat, Latitude) else Latitude(lat)
+        lon = (
+            lon
+            if (isinstance(lon, Longitude) and lon.dtype == np.float64)
+            else Longitude(lon, dtype=np.float64)
+        )
+        lat = (
+            lat
+            if (isinstance(lat, Latitude) and lat.dtype == np.float64)
+            else Latitude(lat, dtype=np.float64)
+        )
         return function(lon, lat, *args, **kwargs)
 
     return _validate_lonlat_wrap