TST, ENH: make all comparisons with NaT false

Now, NaT compares like NaN:
- NaT != NaT -> True
- NaT == NaT (and all other comparisons) -> False

We discussed this on the mailing list back in October:
https://mail.scipy.org/pipermail/numpy-discussion/2015-October/073968.html

1 files changed, 3 insertions, 3 deletions

diff --git a/numpy/core/arrayprint.py b/numpy/core/arrayprint.py
index fefcb6493..c5b5b5a8f 100644
--- a/numpy/core/arrayprint.py
+++ b/numpy/core/arrayprint.py
@@ -739,8 +739,8 @@ class DatetimeFormat(object):
 class TimedeltaFormat(object):
     def __init__(self, data):
         if data.dtype.kind == 'm':
-            nat_value = array(['NaT'], dtype=data.dtype)[0]
-            v = data[not_equal(data, nat_value)].view('i8')
+            # select non-NaT elements
+            v = data[data == data].view('i8')
             if len(v) > 0:
                 # Max str length of non-NaT elements
                 max_str_len = max(len(str(maximum.reduce(v))),
@@ -754,7 +754,7 @@ class TimedeltaFormat(object):
             self._nat = "'NaT'".rjust(max_str_len)
 
     def __call__(self, x):
-        if x + 1 == x:
+        if x != x:
             return self._nat
         else:
             return self.format % x.astype('i8')