BUG: isnull works with float32, address GH #182

Author: wesm

pandas/src/tseries.pyx

@@ -227,7 +227,7 @@ cdef inline _isnan(object o):
     return o != o
 
 cdef inline _checknull(object val):
-    if isinstance(val, float):
+    if isinstance(val, (float, np.floating)):
         return val != val or val == INF or val == NEGINF
     else:
         return val is None

pandas/tests/test_frame.py

@@ -1548,6 +1548,17 @@ def test_to_csv_multiindex(self):
 
         os.remove(path)
 
+    def test_to_csv_float32_nanrep(self):
+        df = DataFrame(np.random.randn(1, 4).astype(np.float32))
+        df[1] = np.nan
+
+        pth = '__tmp__.csv'
+        df.to_csv(pth, nanRep=999)
+
+        lines = open(pth).readlines()
+        self.assert_(lines[1].split(',')[2] == '999')
+        os.remove(pth)
+
     def test_info(self):
         io = StringIO()
         self.frame.info(buf=io)