BUG: astype falsely converts inf to integer (GH14265) (pandas-dev#14343)

Author: shawnheide

doc/source/whatsnew/v0.20.0.txt

@@ -118,3 +118,5 @@ Performance Improvements
 
 Bug Fixes
 ~~~~~~~~~
+
+- Bug in ``astype()`` where ``inf`` values were incorrectly converted to integers. Now raises error now with ``astype()`` for Series and DataFrames (:issue:`14265`)

pandas/sparse/tests/test_array.py

@@ -361,7 +361,7 @@ def test_astype(self):
             arr.astype('i8')
 
         arr = SparseArray([0, np.nan, 0, 1], fill_value=0)
-        msg = "Cannot convert NA to integer"
+        msg = 'Cannot convert non-finite values \(NA or inf\) to integer'
         with tm.assertRaisesRegexp(ValueError, msg):
             arr.astype('i8')
 

pandas/tests/frame/test_dtypes.py

@@ -353,9 +353,17 @@ def test_astype_with_view(self):
         tf = self.frame.astype(np.float64)
         casted = tf.astype(np.int64, copy=False)  # noqa
 
-    def test_astype_cast_nan_int(self):
-        df = DataFrame(data={"Values": [1.0, 2.0, 3.0, np.nan]})
-        self.assertRaises(ValueError, df.astype, np.int64)
+    def test_astype_cast_nan_inf_int(self):
+        # GH14265, check nan and inf raise error when converting to int
+        types = [np.int32, np.int64]
+        values = [np.nan, np.inf]
+        msg = 'Cannot convert non-finite values \(NA or inf\) to integer'
+
+        for this_type in types:
+            for this_val in values:
+                df = DataFrame([this_val])
+                with tm.assertRaisesRegexp(ValueError, msg):
+                    df.astype(this_type)
 
     def test_astype_str(self):
         # GH9757

pandas/tests/series/test_dtypes.py

@@ -42,9 +42,17 @@ def test_dtype(self):
         assert_series_equal(self.ts.get_ftype_counts(), Series(
             1, ['float64:dense']))
 
-    def test_astype_cast_nan_int(self):
-        df = Series([1.0, 2.0, 3.0, np.nan])
-        self.assertRaises(ValueError, df.astype, np.int64)
+    def test_astype_cast_nan_inf_int(self):
+        # GH14265, check nan and inf raise error when converting to int
+        types = [np.int32, np.int64]
+        values = [np.nan, np.inf]
+        msg = 'Cannot convert non-finite values \(NA or inf\) to integer'
+
+        for this_type in types:
+            for this_val in values:
+                s = Series([this_val])
+                with self.assertRaisesRegexp(ValueError, msg):
+                    s.astype(this_type)
 
     def test_astype_cast_object_int(self):
         arr = Series(["car", "house", "tree", "1"])

pandas/types/cast.py

@@ -527,8 +527,10 @@ def _astype_nansafe(arr, dtype, copy=True):
     elif (np.issubdtype(arr.dtype, np.floating) and
           np.issubdtype(dtype, np.integer)):
 
-        if np.isnan(arr).any():
-            raise ValueError('Cannot convert NA to integer')
+        if not np.isfinite(arr).all():
+            raise ValueError('Cannot convert non-finite values (NA or inf) to '
+                             'integer')
+
     elif arr.dtype == np.object_ and np.issubdtype(dtype.type, np.integer):
         # work around NumPy brokenness, #1987
         return lib.astype_intsafe(arr.ravel(), dtype).reshape(arr.shape)