Add border_width checks

photutils/detection/peakfinder.py

@@ -19,7 +19,7 @@
 
 
 def find_peaks(data, threshold, *, box_size=3, footprint=None, mask=None,
-               border_width=None, npeaks=np.inf, centroid_func=None,
+               border_width=0, npeaks=np.inf, centroid_func=None,
                error=None, wcs=None):
     """
     Find local peaks in an image that are above a specified threshold
@@ -74,9 +74,9 @@ def find_peaks(data, threshold, *, box_size=3, footprint=None, mask=None,
         A boolean mask with the same shape as ``data``, where a `True`
         value indicates the corresponding element of ``data`` is masked.
 
-    border_width : bool, optional
+    border_width : int, optional
         The width in pixels to exclude around the border of the
-        ``data``.
+        ``data``. Must be an non-negative integer.
 
     npeaks : int, optional
         The maximum number of peaks to return. When the number of
@@ -126,7 +126,6 @@ def find_peaks(data, threshold, *, box_size=3, footprint=None, mask=None,
     arrays, unit = process_quantities((data, threshold, error),
                                       ('data', 'threshold', 'error'))
     data, threshold, error = arrays
-
     data = np.asanyarray(data)
 
     if np.all(data == data.flat[0]):
@@ -140,6 +139,11 @@ def find_peaks(data, threshold, *, box_size=3, footprint=None, mask=None,
             raise ValueError('A threshold array must have the same shape as '
                              'the input data.')
 
+    if border_width < 0:
+        raise ValueError('border_width must be a non-negative integer.')
+    if int(border_width) != border_width:
+        raise ValueError('border_width must be an integer.')
+
     # remove NaN values to avoid runtime warnings
     nan_mask = np.isnan(data)
     if np.any(nan_mask):
@@ -161,7 +165,7 @@ def find_peaks(data, threshold, *, box_size=3, footprint=None, mask=None,
             raise ValueError('data and mask must have the same shape')
         peak_goodmask = np.logical_and(peak_goodmask, ~mask)
 
-    if border_width is not None:
+    if border_width > 0:
         for i in range(peak_goodmask.ndim):
             peak_goodmask = peak_goodmask.swapaxes(0, i)
             peak_goodmask[:border_width] = False

photutils/detection/tests/test_peakfinder.py

@@ -91,6 +91,13 @@ def test_border_width(self, data):
         tbl1 = find_peaks(data, 0.1, box_size=3, border_width=25)
         assert len(tbl1) < len(tbl0)
 
+        match = 'border_width must be a non-negative integer'
+        with pytest.raises(ValueError, match=match):
+            find_peaks(data, 0.1, box_size=3, border_width=-1)
+        match = 'border_width must be an integer'
+        with pytest.raises(ValueError, match=match):
+            find_peaks(data, 0.1, box_size=3, border_width=3.1)
+
     def test_box_size_int(self, data):
         """
         Test non-integer box_size.