Merge pull request #397 from esheldon/empty-slice

FIX empty slice case

CHANGES.md

@@ -1,3 +1,10 @@
+version 1.2.3 (not yet released)
+-------------
+
+Bug Fixes
+
+    - Reading images with empty slices was returning data
+
 version 1.2.2
 -------------
 

fitsio/__init__.py

@@ -5,7 +5,7 @@
 usage.
 """
 
-__version__ = '1.2.2'
+__version__ = '1.2.3'
 
 from . import fitslib
 

fitsio/hdu/image.py

@@ -278,8 +278,11 @@ def _read_image_slice(self, arg):
                     step = -1
 
             # Sanity checks for proper syntax.
-            if (step > 0 and stop < start) or (step < 0 and start < stop):
+            if ((step > 0 and stop < start)
+                    or (step < 0 and start < stop)
+                    or (start == stop)):
                 return numpy.empty(0, dtype=npy_dtype)
+
             if start < 0:
                 start = dims[dim] + start
                 if start < 0:
@@ -293,6 +296,7 @@ def _read_image_slice(self, arg):
 
             if stop > dims[dim]:
                 stop = dims[dim]
+
             if stop < start:
                 # A little black magic here.  The stop is offset by 2 to
                 # accommodate the 1-offset of CFITSIO, and to move past the end

fitsio/tests/test_empty_slice.py

@@ -0,0 +1,21 @@
+import tempfile
+import os
+import numpy as np
+from ..fitslib import write, FITS
+
+
+def test_empty_image_slice():
+
+    shape = (10, 10)
+    data = np.arange(shape[0] * shape[1]).reshape(shape)
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        fname = os.path.join(tmpdir, 'test.fits')
+        write(fname, data, clobber=True)
+
+        with FITS(fname) as fits:
+            assert fits[0][0:0, 0:0].size == 0
+
+            assert fits[0][0:8, 0:0].size == 0
+
+            assert fits[0][0:0, 0:8].size == 0

setup.py

@@ -318,7 +318,7 @@ def check_system_cfitsio_objects(self, obj_name):
 
 setup(
     name="fitsio",
-    version="1.2.2",
+    version="1.2.3",
     description=description,
     long_description=long_description,
     long_description_content_type='text/markdown; charset=UTF-8; variant=GFM',