Allow only axis=0 and axis=None for 0-d arrays, and disallow axis>MAX_DIMS (addresses #1286)

These changes should catch errors earlier by raising exceptions, instead
of resulting to unexpected behavior.

2 files changed, 20 insertions, 2 deletions

diff --git a/numpy/core/src/multiarray/ctors.c b/numpy/core/src/multiarray/ctors.c
index a07998a8c..80a9d7988 100644
--- a/numpy/core/src/multiarray/ctors.c
+++ b/numpy/core/src/multiarray/ctors.c
@@ -2424,6 +2424,9 @@ PyArray_CopyInto(PyArrayObject *dest, PyArrayObject *src)
 
 /*NUMPY_API
   PyArray_CheckAxis
+
+  check that axis is valid
+  convert 0-d arrays to 1-d arrays
 */
 NPY_NO_EXPORT PyObject *
 PyArray_CheckAxis(PyArrayObject *arr, int *axis, int flags)
@@ -2431,14 +2434,16 @@ PyArray_CheckAxis(PyArrayObject *arr, int *axis, int flags)
     PyObject *temp1, *temp2;
     int n = arr->nd;
 
-    if ((*axis >= MAX_DIMS) || (n==0)) {
+    if (*axis == MAX_DIMS || n == 0) {
         if (n != 1) {
             temp1 = PyArray_Ravel(arr,0);
             if (temp1 == NULL) {
                 *axis = 0;
                 return NULL;
             }
-            *axis = PyArray_NDIM(temp1)-1;
+            if (*axis == MAX_DIMS) {
+                *axis = PyArray_NDIM(temp1)-1;
+            }
         }
         else {
             temp1 = (PyObject *)arr;
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 8c426bc5f..f40e5e9ca 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -644,6 +644,19 @@ class TestArgmax(TestCase):
             axes.remove(i)
             assert all(amax == aargmax.choose(*a.transpose(i,*axes)))
 
+class TestMinMax(TestCase):
+    def test_scalar(self):
+        assert_raises(ValueError, np.amax, 1, 1)
+        assert_raises(ValueError, np.amin, 1, 1)
+
+        assert_equal(np.amax(1, axis=0), 1)
+        assert_equal(np.amin(1, axis=0), 1)
+        assert_equal(np.amax(1, axis=None), 1)
+        assert_equal(np.amin(1, axis=None), 1)
+
+    def test_axis(self):
+        assert_raises(ValueError, np.amax, [1,2,3], 1000)
+        assert_equal(np.amax([[1,2,3]], axis=1), 3)
 
 class TestNewaxis(TestCase):
     def test_basic(self):