numpy · charris · Aug 6, 2017 · Aug 1, 2017 · Aug 1, 2017 · Aug 1, 2017
diff --git a/doc/release/1.14.0-notes.rst b/doc/release/1.14.0-notes.rst
@@ -25,6 +25,17 @@ Deprecations
 Future Changes
 ==============
 
+``np.issubdtype`` will stop downcasting dtype-like arguments
+------------------------------------------------------------
+It would be expected that ``issubdtype(np.float32, 'float64')`` and
+``issubdtype(np.float32, np.float64)`` mean the same thing - however, there
+was an undocumented special case that translated the former into
+``issubdtype(np.float32, np.floating)``, giving the surprising result of True.
+
+This translation now gives a warning explaining what translation is occuring.
+In future, the translation will be disabled, and the first example will be made
+equivalent to the second.
+
 
 Build System Changes
 ====================

diff --git a/numpy/core/function_base.py b/numpy/core/function_base.py
@@ -339,7 +339,7 @@ def geomspace(start, stop, num=50, endpoint=True, dtype=None):
     # complex and another is negative and log would produce NaN otherwise
     start = start + (stop - stop)
     stop = stop + (start - start)
-    if _nx.issubdtype(dtype, complex):
+    if _nx.issubdtype(dtype, _nx.complexfloating):
         start = start + 0j
         stop = stop + 0j
 

diff --git a/numpy/core/numeric.py b/numpy/core/numeric.py
@@ -436,8 +436,7 @@ def count_nonzero(a, axis=None):
     if issubdtype(a.dtype, np.number):
         return (a != 0).sum(axis=axis, dtype=np.intp)
 
-    if (issubdtype(a.dtype, np.string_) or
-            issubdtype(a.dtype, np.unicode_)):
+    if issubdtype(a.dtype, np.character):
         nullstr = a.dtype.type('')
         return (a != nullstr).sum(axis=axis, dtype=np.intp)
 

diff --git a/numpy/core/numerictypes.py b/numpy/core/numerictypes.py
@@ -85,6 +85,7 @@
 import types as _types
 import sys
 import numbers
+import warnings
 
 from numpy.compat import bytes, long
 from numpy.core.multiarray import (
@@ -745,20 +746,46 @@ def issubdtype(arg1, arg2):
 
     Examples
     --------
-    >>> np.issubdtype('S1', str)
+    >>> np.issubdtype('S1', np.string_)
     True
     >>> np.issubdtype(np.float64, np.float32)
     False
 
     """
-    if issubclass_(arg2, generic):
-        return issubclass(dtype(arg1).type, arg2)
-    mro = dtype(arg2).type.mro()
-    if len(mro) > 1:
-        val = mro[1]
-    else:
-        val = mro[0]
-    return issubclass(dtype(arg1).type, val)
+    if not issubclass_(arg1, generic):
+        arg1 = dtype(arg1).type
+    if not issubclass_(arg2, generic):
+        arg2_orig = arg2
+        arg2 = dtype(arg2).type
+        if not isinstance(arg2_orig, dtype):
+            # weird deprecated behaviour, that tried to infer np.floating from
+            # float, and similar less obvious things, such as np.generic from
+            # basestring
+            mro = arg2.mro()
+            arg2 = mro[1] if len(mro) > 1 else mro[0]
+
+            def type_repr(x):
+                """ Helper to produce clear error messages """
+                if not isinstance(x, type):
+                    return repr(x)
+                elif issubclass(x, generic):
+                    return "np.{}".format(x.__name__)
+                else:
+                    return x.__name__
+
+            # 1.14, 2017-08-01
+            warnings.warn(
+                "Conversion of the second argument of issubdtype from `{raw}` "
+                "to `{abstract}` is deprecated. In future, it will be treated "
+                "as `{concrete} == np.dtype({raw}).type`.".format(
+                    raw=type_repr(arg2_orig),
+                    abstract=type_repr(arg2),
+                    concrete=type_repr(dtype(arg2_orig).type)
+                ),
+                FutureWarning, stacklevel=2
+            )
+
+    return issubclass(arg1, arg2)
 
 
 # This dictionary allows look up based on any alias for an array data-type

diff --git a/numpy/core/tests/test_numerictypes.py b/numpy/core/tests/test_numerictypes.py
@@ -1,6 +1,7 @@
 from __future__ import division, absolute_import, print_function
 
 import sys
+import itertools
 
 import numpy as np
 from numpy.testing import (
@@ -377,5 +378,36 @@ def test_return(self):
         res = self.ary[['f0', 'f2']].tolist()
         assert_(res == [(1, 3), (5, 7)])
 
+
+class TestIsSubDType(object):
+    # scalar types can be promoted into dtypes
+    wrappers = [np.dtype, lambda x: x]
+
+    def test_both_abstract(self):
+        assert_(np.issubdtype(np.floating, np.inexact))
+        assert_(not np.issubdtype(np.inexact, np.floating))
+
+    def test_same(self):
+        for cls in (np.float32, np.int32):
+            for w1, w2 in itertools.product(self.wrappers, repeat=2):
+                assert_(np.issubdtype(w1(cls), w2(cls)))
+
+    def test_subclass(self):
+        # note we cannot promote floating to a dtype, as it would turn into a
+        # concrete type
+        for w in self.wrappers:
+            assert_(np.issubdtype(w(np.float32), np.floating))
+            assert_(np.issubdtype(w(np.float64), np.floating))
+
+    def test_subclass_backwards(self):
+        for w in self.wrappers:
+            assert_(not np.issubdtype(np.floating, w(np.float32)))
+            assert_(not np.issubdtype(np.floating, w(np.float64)))
+
+    def test_sibling_class(self):
+        for w1, w2 in itertools.product(self.wrappers, repeat=2):
+            assert_(not np.issubdtype(w1(np.float32), w2(np.float64)))
+            assert_(not np.issubdtype(w1(np.float64), w2(np.float32)))
+
 if __name__ == "__main__":
     run_module_suite()
diff --git a/numpy/doc/basics.py b/numpy/doc/basics.py
@@ -114,10 +114,10 @@
     >>> d
     dtype('int32')
 
-    >>> np.issubdtype(d, int)
+    >>> np.issubdtype(d, np.integer)
     True
 
-    >>> np.issubdtype(d, float)
+    >>> np.issubdtype(d, np.floating)
     False
 
 

diff --git a/numpy/lib/_iotools.py b/numpy/lib/_iotools.py
@@ -527,7 +527,7 @@ class StringConverter(object):
         _mapper.append((nx.int64, int, -1))
 
     _mapper.extend([(nx.floating, float, nx.nan),
-                    (complex, _bytes_to_complex, nx.nan + 0j),
+                    (nx.complexfloating, _bytes_to_complex, nx.nan + 0j),
                     (nx.longdouble, nx.longdouble, nx.nan),
                     (nx.string_, bytes, b'???')])
 

diff --git a/numpy/lib/tests/test_function_base.py b/numpy/lib/tests/test_function_base.py
@@ -1711,16 +1711,16 @@ def test_type(self):
         # Check the type of the returned histogram
         a = np.arange(10) + .5
         h, b = histogram(a)
-        assert_(np.issubdtype(h.dtype, int))
+        assert_(np.issubdtype(h.dtype, np.integer))
 
         h, b = histogram(a, normed=True)
-        assert_(np.issubdtype(h.dtype, float))
+        assert_(np.issubdtype(h.dtype, np.floating))
 
         h, b = histogram(a, weights=np.ones(10, int))
-        assert_(np.issubdtype(h.dtype, int))
+        assert_(np.issubdtype(h.dtype, np.integer))
 
         h, b = histogram(a, weights=np.ones(10, float))
-        assert_(np.issubdtype(h.dtype, float))
+        assert_(np.issubdtype(h.dtype, np.floating))
 
     def test_f32_rounding(self):
         # gh-4799, check that the rounding of the edges works with float32

diff --git a/numpy/lib/tests/test_index_tricks.py b/numpy/lib/tests/test_index_tricks.py
@@ -243,7 +243,7 @@ def test_shape_and_dtype(self):
             for k, (a, sz) in enumerate(zip(arrays, sizes)):
                 assert_equal(a.shape[k], sz)
                 assert_(all(sh == 1 for j, sh in enumerate(a.shape) if j != k))
-                assert_(np.issubdtype(a.dtype, int))
+                assert_(np.issubdtype(a.dtype, np.integer))
 
     def test_bool(self):
         bool_a = [True, False, True, True]

diff --git a/numpy/lib/tests/test_type_check.py b/numpy/lib/tests/test_type_check.py
@@ -420,7 +420,7 @@ class TestArrayConversion(object):
     def test_asfarray(self):
         a = asfarray(np.array([1, 2, 3]))
         assert_equal(a.__class__, np.ndarray)
-        assert_(np.issubdtype(a.dtype, float))
+        assert_(np.issubdtype(a.dtype, np.floating))
 
 if __name__ == "__main__":
     run_module_suite()
diff --git a/numpy/matrixlib/defmatrix.py b/numpy/matrixlib/defmatrix.py
@@ -137,7 +137,7 @@ def matrix_power(M, n):
     M = asanyarray(M)
     if M.ndim != 2 or M.shape[0] != M.shape[1]:
         raise ValueError("input must be a square array")
-    if not issubdtype(type(n), int):
+    if not issubdtype(type(n), N.integer):
         raise TypeError("exponent must be an integer")
 
     from numpy.linalg import inv

diff --git a/numpy/matrixlib/tests/test_defmatrix.py b/numpy/matrixlib/tests/test_defmatrix.py
@@ -249,6 +249,12 @@ def test_pow(self):
         assert_array_almost_equal(m4, np.dot(m2, m2))
         assert_array_almost_equal(np.dot(mi, m), np.eye(2))
 
+    def test_scalar_type_pow(self):
+        m = matrix([[1, 2], [3, 4]])
+        for scalar_t in [np.int8, np.uint8]:
+            two = scalar_t(2)
+            assert_array_almost_equal(m ** 2, m ** two)
+
     def test_notimplemented(self):
         '''Check that 'not implemented' operations produce a failure.'''
         A = matrix([[1., 2.],