Simplify implementation of is_numlike & is_string_like.

anntzer · anntzer · commit 6b716cf79d44 · 2017-01-30T21:36:28.000-08:00
diff --git a/doc/api/api_changes/2017-01-30-AL_is_numlike_stringlike.rst b/doc/api/api_changes/2017-01-30-AL_is_numlike_stringlike.rst
@@ -0,0 +1,8 @@
+`cbook.is_numlike` and `cbook.is_string_like` only perform an instance check
+````````````````````````````````````````````````````````````````````````````
+
+`cbook.is_numlike` and `cbook.is_string_like` now only check that
+their argument is an instance of ``(numbers.Number, np.Number)`` and
+``(six.string_types, np.str_, np.unicode_)`` respectively.  In particular, this
+means that arrays are now never num-like or string-like regardless of their
+dtype.
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
@@ -20,6 +20,7 @@
 import gzip
 import io
 import locale
+import numbers
 import os
 import re
 import sys
@@ -495,19 +496,8 @@ def iterable(obj):
 
 def is_string_like(obj):
     """Return True if *obj* looks like a string"""
-    if isinstance(obj, six.string_types):
-        return True
-    # numpy strings are subclass of str, ma strings are not
-    if isinstance(obj, np.ma.MaskedArray):
-        if obj.ndim == 0 and obj.dtype.kind in 'SU':
-            return True
-        else:
-            return False
-    try:
-        obj + ''
-    except:
-        return False
-    return True
+    # (np.str_ == np.unicode_ on Py3).
+    return isinstance(obj, (six.string_types, np.str_, np.unicode_))
 
 
 def is_sequence_of_strings(obj):
@@ -560,12 +550,7 @@ def is_scalar(obj):
 
 def is_numlike(obj):
     """return true if *obj* looks like a number"""
-    try:
-        obj + 1
-    except:
-        return False
-    else:
-        return True
+    return isinstance(obj, (numbers.Number, np.number))
 
 
 def to_filehandle(fname, flag='rU', return_opened=False):
diff --git a/lib/matplotlib/tests/test_cbook.py b/lib/matplotlib/tests/test_cbook.py
@@ -34,9 +34,6 @@ def test_is_string_like():
     y = np.array(y)
     assert not cbook.is_string_like(y)
 
-    y = np.array(y, dtype=object)
-    assert cbook.is_string_like(y)
-
 
 def test_is_sequence_of_strings():
     y = ['a', 'b', 'c']
