MAINT: Change the type of error raised in set_printoptions (gh-13899)

Previously an incorrect ``threshold`` raised ``ValueError``; it now raises ``TypeError``
for non-numeric types and ``ValueError`` for ``nan`` values.

2 files changed, 7 insertions, 5 deletions

diff --git a/numpy/core/arrayprint.py b/numpy/core/arrayprint.py
index 108364824..ecd05d3ac 100644
--- a/numpy/core/arrayprint.py
+++ b/numpy/core/arrayprint.py
@@ -89,8 +89,10 @@ def _make_options_dict(precision=None, threshold=None, edgeitems=None,
                       "`False`", stacklevel=3)
     if threshold is not None:
         # forbid the bad threshold arg suggested by stack overflow, gh-12351
-        if not isinstance(threshold, numbers.Number) or np.isnan(threshold):
-            raise ValueError("threshold must be numeric and non-NAN, try "
+        if not isinstance(threshold, numbers.Number):
+            raise TypeError("threshold must be numeric")
+        if np.isnan(threshold):
+            raise ValueError("threshold must be non-NAN, try "
                              "sys.maxsize for untruncated representation")
     return options
 
diff --git a/numpy/core/tests/test_arrayprint.py b/numpy/core/tests/test_arrayprint.py
index f2b8fdca7..75a794369 100644
--- a/numpy/core/tests/test_arrayprint.py
+++ b/numpy/core/tests/test_arrayprint.py
@@ -847,9 +847,9 @@ class TestPrintOptions(object):
         )
 
     def test_bad_args(self):
-        assert_raises(ValueError, np.set_printoptions, threshold='nan')
-        assert_raises(ValueError, np.set_printoptions, threshold=u'1')
-        assert_raises(ValueError, np.set_printoptions, threshold=b'1')
+        assert_raises(ValueError, np.set_printoptions, threshold=float('nan'))
+        assert_raises(TypeError, np.set_printoptions, threshold='1')
+        assert_raises(TypeError, np.set_printoptions, threshold=b'1')
 
 def test_unicode_object_array():
     import sys