From 50ef0e60b9a6e9ed6df430abf3675d0601b33919 Mon Sep 17 00:00:00 2001
From: Vikram Bhandoh <vikram@newmanonline.org.uk>
Date: Sat, 29 Nov 2014 12:31:05 +0000
Subject: [PATCH 1/2] astype checks notnull Fixes: #8732

---
 pandas/core/internals.py   | 5 ++++-
 pandas/tests/test_frame.py | 9 +++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/pandas/core/internals.py b/pandas/core/internals.py
index ef33e27d861fd..750b47786dec3 100644
--- a/pandas/core/internals.py
+++ b/pandas/core/internals.py
@@ -398,7 +398,10 @@ def _astype(self, dtype, copy=False, raise_on_error=True, values=None,
             # force the copy here
             if values is None:
                 # _astype_nansafe works fine with 1-d only
-                values = com._astype_nansafe(self.values.ravel(), dtype, copy=True)
+                if isnull(self.values).any():
+                    values = com._astype_nansafe(self.values.ravel(), dtype, copy=True)
+                else:
+                    values = self.values.ravel().astype(dtype)
                 values = values.reshape(self.values.shape)
             newb = make_block(values,
                               ndim=self.ndim, placement=self.mgr_locs,
diff --git a/pandas/tests/test_frame.py b/pandas/tests/test_frame.py
index fc031afe728dc..da5f83935f31e 100644
--- a/pandas/tests/test_frame.py
+++ b/pandas/tests/test_frame.py
@@ -2141,6 +2141,15 @@ def setUp(self):
         self.simple = DataFrame(arr, columns=['one', 'two', 'three'],
                                 index=['a', 'b', 'c'])
 
+    def test_hasnulls(self):
+        df = tm.makeMissingDataframe()
+        self.assertEqual(df['A'].notnull().all(), False)
+        casted = df.astype(np.float64)
+        expected = DataFrame(df.values.astype(np.float64),
+                             index=df.index,
+                             columns=df.columns)
+        assert_frame_equal(casted, expected)
+
     def test_get_axis(self):
         f = self.frame
         self.assertEqual(f._get_axis_number(0), 0)

From ec8f6b5e50af4b591daceaf128dd245df4b80a76 Mon Sep 17 00:00:00 2001
From: Vikram Bhandoh <vikram@newmanonline.org.uk>
Date: Sat, 29 Nov 2014 13:13:03 +0000
Subject: [PATCH 2/2] added benchmark

---
 pandas/tests/test_frame.py |  7 +++++++
 vb_suite/astype.py         | 14 ++++++++++++++
 vb_suite/suite.py          |  1 +
 3 files changed, 22 insertions(+)
 create mode 100644 vb_suite/astype.py

diff --git a/pandas/tests/test_frame.py b/pandas/tests/test_frame.py
index da5f83935f31e..e19f5a0ff8719 100644
--- a/pandas/tests/test_frame.py
+++ b/pandas/tests/test_frame.py
@@ -2142,6 +2142,7 @@ def setUp(self):
                                 index=['a', 'b', 'c'])
 
     def test_hasnulls(self):
+        # Github Issue 8732
         df = tm.makeMissingDataframe()
         self.assertEqual(df['A'].notnull().all(), False)
         casted = df.astype(np.float64)
@@ -2150,6 +2151,12 @@ def test_hasnulls(self):
                              columns=df.columns)
         assert_frame_equal(casted, expected)
 
+        casted = df.astype(np.str)
+        expected = DataFrame(df.values.astype(np.str),
+                             index=df.index,
+                             columns=df.columns)
+        assert_frame_equal(casted, expected)
+
     def test_get_axis(self):
         f = self.frame
         self.assertEqual(f._get_axis_number(0), 0)
diff --git a/vb_suite/astype.py b/vb_suite/astype.py
new file mode 100644
index 0000000000000..26deab3a145cb
--- /dev/null
+++ b/vb_suite/astype.py
@@ -0,0 +1,14 @@
+from vbench.api import Benchmark
+
+common_setup = """from pandas_vb_common import *
+from datetime import timedelta
+import numpy as np
+
+N = 1000000
+arr = np.random.randint(1,10,size=1000000)
+s = pd.Series(arr)
+"""
+
+astype_test = Benchmark('s.astype(np.str)',
+                        common_setup,
+                        name='astype_test')
diff --git a/vb_suite/suite.py b/vb_suite/suite.py
index a16d183ae62e2..ee5a49dac2e66 100644
--- a/vb_suite/suite.py
+++ b/vb_suite/suite.py
@@ -13,6 +13,7 @@
            'indexing',
            'io_bench',
            'io_sql',
+           'astype',
            'inference',
            'hdfstore_bench',
            'join_merge',