Merge pull request #2245 from larrybradley/check-units

larrybradley · web-flow · commit 1a07a834c0b5 · 2026-04-03T11:10:44.000-04:00
Add check_units (private) helper function
diff --git a/photutils/detection/core.py b/photutils/detection/core.py
@@ -24,7 +24,7 @@
                                           deprecated_positional_kwargs,
                                           deprecated_renamed_argument)
 from photutils.utils._misc import _get_meta
-from photutils.utils._quantity_helpers import process_quantities
+from photutils.utils._quantity_helpers import check_units
 from photutils.utils._repr import make_repr
 from photutils.utils.cutouts import _make_cutouts
 from photutils.utils.exceptions import NoDetectionsWarning
@@ -221,10 +221,8 @@ class StarFinderCatalogBase(metaclass=abc.ABCMeta):
     @deprecated_renamed_argument('peakmax', 'peak_max', '3.0', until='4.0')
     def __init__(self, data, xypos, kernel, *, n_brightest=None,
                  peak_max=None):
-        # Validate the units, but do not strip them
-        inputs = (data, peak_max)
-        names = ('data', 'peak_max')
-        _ = process_quantities(inputs, names)
+        # Validate the units
+        check_units((data, peak_max), ('data', 'peak_max'))
 
         self.data = data
         unit = data.unit if isinstance(data, u.Quantity) else None
diff --git a/photutils/detection/daofinder.py b/photutils/detection/daofinder.py
@@ -16,7 +16,7 @@
 from photutils.utils._convolution import _filter_data
 from photutils.utils._deprecation import (deprecated_positional_kwargs,
                                           deprecated_renamed_argument)
-from photutils.utils._quantity_helpers import isscalar, process_quantities
+from photutils.utils._quantity_helpers import check_units, isscalar
 from photutils.utils._repr import make_repr
 from photutils.utils.exceptions import NoDetectionsWarning
 
@@ -219,7 +219,7 @@ def __init__(self, threshold, fwhm, ratio=1.0, theta=0.0,
         # Validate the units, but do not strip them
         inputs = (threshold, peak_max)
         names = ('threshold', 'peak_max')
-        _ = process_quantities(inputs, names)
+        check_units(inputs, names)
 
         if not isscalar(fwhm):
             msg = 'fwhm must be a scalar value'
@@ -399,7 +399,7 @@ def find_stars(self, data, mask=None):
         # Validate the units, but do not strip them
         inputs = (data, self.threshold, self.peak_max)
         names = ('data', 'threshold', 'peak_max')
-        _ = process_quantities(inputs, names)
+        check_units(inputs, names)
 
         cat = self._get_raw_catalog(data, mask=mask)
         if cat is None:
@@ -476,7 +476,7 @@ def __init__(self, data, convolved_data, xypos, threshold, kernel, *,
         # Validate the units, but do not strip them
         inputs = (data, convolved_data, threshold, peak_max)
         names = ('data', 'convolved_data', 'threshold', 'peak_max')
-        _ = process_quantities(inputs, names)
+        check_units(inputs, names)
 
         super().__init__(data, xypos, kernel,
                          n_brightest=n_brightest,
diff --git a/photutils/detection/irafstarfinder.py b/photutils/detection/irafstarfinder.py
@@ -16,7 +16,7 @@
 from photutils.utils._convolution import _filter_data
 from photutils.utils._deprecation import (deprecated_positional_kwargs,
                                           deprecated_renamed_argument)
-from photutils.utils._quantity_helpers import isscalar, process_quantities
+from photutils.utils._quantity_helpers import check_units, isscalar
 from photutils.utils._repr import make_repr
 from photutils.utils.exceptions import NoDetectionsWarning
 
@@ -184,7 +184,7 @@ def __init__(self, threshold, fwhm, sigma_radius=1.5,
         # Validate the units, but do not strip them
         inputs = (threshold, peak_max)
         names = ('threshold', 'peak_max')
-        _ = process_quantities(inputs, names)
+        check_units(inputs, names)
 
         if not isscalar(fwhm):
             msg = 'fwhm must be a scalar value'
@@ -364,7 +364,7 @@ def find_stars(self, data, mask=None):
         """
         inputs = (data, self.threshold, self.peak_max)
         names = ('data', 'threshold', 'peak_max')
-        _ = process_quantities(inputs, names)
+        check_units(inputs, names)
 
         cat = self._get_raw_catalog(data, mask=mask)
         if cat is None:
@@ -434,7 +434,7 @@ def __init__(self, data, convolved_data, xypos, kernel, *,
         # Validate the units, but do not strip them
         inputs = (data, convolved_data, peak_max)
         names = ('data', 'convolved_data', 'peak_max')
-        _ = process_quantities(inputs, names)
+        check_units(inputs, names)
 
         super().__init__(data, xypos, kernel,
                          n_brightest=n_brightest,
diff --git a/photutils/detection/starfinder.py b/photutils/detection/starfinder.py
@@ -13,7 +13,7 @@
 from photutils.utils._convolution import _filter_data
 from photutils.utils._deprecation import (deprecated_positional_kwargs,
                                           deprecated_renamed_argument)
-from photutils.utils._quantity_helpers import process_quantities
+from photutils.utils._quantity_helpers import check_units
 from photutils.utils._repr import make_repr
 from photutils.utils.exceptions import NoDetectionsWarning
 
@@ -88,10 +88,8 @@ class StarFinder(StarFinderBase):
     def __init__(self, threshold, kernel, min_separation=None,
                  exclude_border=False, n_brightest=None, peak_max=None):
 
-        # Validate the units, but do not strip them
-        inputs = (threshold, peak_max)
-        names = ('threshold', 'peak_max')
-        _ = process_quantities(inputs, names)
+        # Validate the units
+        check_units((threshold, peak_max), ('threshold', 'peak_max'))
 
         self.threshold = threshold
 
@@ -210,10 +208,9 @@ def find_stars(self, data, mask=None):
             `None` is returned if no stars are found or no stars meet
             the peak_max criteria.
         """
-        # Validate the units, but do not strip them
-        inputs = (data, self.threshold, self.peak_max)
-        names = ('data', 'threshold', 'peak_max')
-        _ = process_quantities(inputs, names)
+        # Validate the units
+        check_units((data, self.threshold, self.peak_max),
+                    ('data', 'threshold', 'peak_max'))
 
         cat = self._get_raw_catalog(data, mask=mask)
         if cat is None:
diff --git a/photutils/segmentation/detect.py b/photutils/segmentation/detect.py
@@ -15,7 +15,7 @@
 from photutils.utils._deprecation import deprecated_renamed_argument
 from photutils.utils._parameters import (SigmaClipSentinelDefault,
                                          create_default_sigmaclip)
-from photutils.utils._quantity_helpers import process_quantities
+from photutils.utils._quantity_helpers import check_units, process_quantities
 from photutils.utils._stats import nanmean, nanstd
 from photutils.utils.exceptions import NoDetectionsWarning
 
@@ -366,7 +366,7 @@ class to detect and deblend sources in a single step.
                    cmap=segm.make_cmap(seed=1234))
         plt.tight_layout()
     """
-    _ = process_quantities((data, threshold), ('data', 'threshold'))
+    check_units((data, threshold), ('data', 'threshold'))
 
     if (n_pixels <= 0) or (int(n_pixels) != n_pixels):
         msg = f'n_pixels must be a positive integer, got {n_pixels!r}'
diff --git a/photutils/utils/_quantity_helpers.py b/photutils/utils/_quantity_helpers.py
@@ -7,15 +7,9 @@
 import numpy as np
 
 
-def process_quantities(values, names):
+def check_units(values, names):
     """
-    Check and remove units of input values.
-
-    If any of the input values have units then they all must have
-    units and the units must be the same.
-
-    The returned values are the input values with units removed and the
-    unit.
+    Check that input values have consistent units.
 
     Parameters
     ----------
@@ -27,18 +21,14 @@ def process_quantities(values, names):
 
     Returns
     -------
-    values : list of scalar or `~numpy.ndarray`
-        A list of values, where units have been removed.
-
-    unit : `~astropy.unit.Unit`
-        The common unit for the input values. `None` will be returned
-        if all the input values do not have units (including when all
-        values are `None`).
+    units : set
+        The set of distinct units across all non-`None` values.
 
     Raises
     ------
     ValueError
-        If the input values do not all have the same units.
+        If the number of values does not match the number of names,
+        or if the input values do not all have the same units.
     """
     if len(values) != len(names):
         msg = 'The number of values must match the number of names.'
@@ -47,9 +37,9 @@ def process_quantities(values, names):
     all_units = {name: getattr(arr, 'unit', None)
                  for arr, name in zip(values, names, strict=True)
                  if arr is not None}
-    unit = set(all_units.values())
+    units = set(all_units.values())
 
-    if len(unit) > 1:
+    if len(units) > 1:
         param_names = list(all_units.keys())
         msg = [f'The inputs {param_names} must all have the same units:']
         indent = ' ' * 4
@@ -61,13 +51,51 @@ def process_quantities(values, names):
         msg = '\n'.join(msg)
         raise ValueError(msg)
 
-    # When all values are None, all_units is empty; return unchanged
+    return units
+
+
+def process_quantities(values, names):
+    """
+    Check and remove units of input values.
+
+    If any of the input values have units then they all must have
+    units and the units must be the same.
+
+    The returned values are the input values with units removed and the
+    unit.
+
+    Parameters
+    ----------
+    values : list of scalar, `~numpy.ndarray`, or `~astropy.units.Quantity`
+        A list of values.
+
+    names : list of str
+        A list of names corresponding to the input ``values``.
+
+    Returns
+    -------
+    values : list of scalar or `~numpy.ndarray`
+        A list of values, where units have been removed.
+
+    unit : `~astropy.unit.Unit`
+        The common unit for the input values. `None` will be returned
+        if all the input values do not have units (including when all
+        values are `None`).
+
+    Raises
+    ------
+    ValueError
+        If the input values do not all have the same units.
+    """
+    units = check_units(values, names)
+
+    # When all values are None, the units set is empty; return unchanged
     # with unit=None
-    if len(unit) == 0:
+    if len(units) == 0:
         return values, None
 
     # Extract the unit and remove it from the return values
-    unit = unit.pop()
+    unit = units.pop()
     if unit is not None:
         values = [val.value if val is not None else val for val in values]
 
diff --git a/photutils/utils/tests/test_quantity_helpers.py b/photutils/utils/tests/test_quantity_helpers.py
@@ -8,7 +8,8 @@
 import pytest
 from numpy.testing import assert_equal
 
-from photutils.utils._quantity_helpers import isscalar, process_quantities
+from photutils.utils._quantity_helpers import (check_units, isscalar,
+                                               process_quantities)
 
 
 @pytest.mark.parametrize('all_units', [False, True])
@@ -30,59 +31,75 @@ def test_units(all_units):
         assert arrs2 == arrs
 
 
+def test_process_quantities_all_none():
+    """
+    Test that process_quantities with all None inputs returns None
+    unit.
+    """
+    values, unit = process_quantities([None, None], ['a', 'b'])
+    assert values == [None, None]
+    assert unit is None
+
+
+def test_isscalar():
+    """
+    Test isscalar with scalar and array inputs.
+    """
+    assert isscalar(1)
+    assert isscalar(1.0 * u.m)
+    assert not isscalar([1, 2, 3])
+    assert not isscalar([1, 2, 3] * u.m)
+
+
+def test_inputs():
+    """
+    Test that mismatched values and names lengths raises ValueError.
+    """
+    match = 'The number of values must match the number of names'
+    with pytest.raises(ValueError, match=match):
+        process_quantities([1, 2, 3], ['a', 'b'])
+    with pytest.raises(ValueError, match=match):
+        check_units([1, 2, 3], ['a', 'b'])
+
+
+def test_check_units():
+    """
+    Test check_units for unit consistency checking.
+    """
+    # Valid: same units
+    check_units((np.ones(3) * u.Jy, np.ones(3) * u.Jy), ('a', 'b'))
+
+    # Valid: no units
+    check_units((np.ones(3), np.ones(3)), ('a', 'b'))
+
+    # Valid: with None values
+    check_units((np.ones(3) * u.Jy, None), ('a', 'b'))
+
+
 def test_mixed_units():
     """
-    Test that process_quantities with mixed units raises ValueError.
+    Test that check_units with mixed units raises ValueError.
     """
     arrs = (np.ones(3) * u.Jy, np.ones(3) * u.km)
     names = ('a', 'b')
 
     match = 'must all have the same units'
     with pytest.raises(ValueError, match=match):
-        _, _ = process_quantities(arrs, names)
+        check_units(arrs, names)
 
     arrs = (np.ones(3) * u.Jy, np.ones(3))
     names = ('a', 'b')
     with pytest.raises(ValueError, match=match):
-        _, _ = process_quantities(arrs, names)
+        check_units(arrs, names)
 
     unit = u.Jy
     arrs = (np.ones(3) * unit, np.ones(3), np.ones(3) * unit)
     names = ('a', 'b', 'c')
     with pytest.raises(ValueError, match=match):
-        _, _ = process_quantities(arrs, names)
+        check_units(arrs, names)
 
     unit = u.Jy
     arrs = (np.ones(3) * unit, np.ones(3), np.ones(3) * u.km)
     names = ('a', 'b', 'c')
     with pytest.raises(ValueError, match=match):
-        _, _ = process_quantities(arrs, names)
-
-
-def test_process_quantities_all_none():
-    """
-    Test that process_quantities with all None inputs returns None
-    unit.
-    """
-    values, unit = process_quantities([None, None], ['a', 'b'])
-    assert values == [None, None]
-    assert unit is None
-
-
-def test_inputs():
-    """
-    Test that mismatched values and names lengths raises ValueError.
-    """
-    match = 'The number of values must match the number of names'
-    with pytest.raises(ValueError, match=match):
-        _, _ = process_quantities([1, 2, 3], ['a', 'b'])
-
-
-def test_isscalar():
-    """
-    Test isscalar with scalar and array inputs.
-    """
-    assert isscalar(1)
-    assert isscalar(1.0 * u.m)
-    assert not isscalar([1, 2, 3])
-    assert not isscalar([1, 2, 3] * u.m)
+        check_units(arrs, names)
