From 75a916a038c62400aa6431c8e9a2deb6e86a350e Mon Sep 17 00:00:00 2001
From: Viktor Kerkez <alefnula@gmail.com>
Date: Fri, 20 Sep 2013 20:57:05 +0200
Subject: [PATCH] Fixed issue #4902.

Extended _ensure_numeric to check if the value is a complex numbers.
Also it now tries to convert the value to a complex number if conversion to float fails.
Added PyDev project files to .gitignore.
---
 .gitignore                  |  3 +++
 doc/source/release.rst      |  1 +
 pandas/core/nanops.py       |  8 +++---
 pandas/tests/test_common.py | 49 +++++++++++++++++++++++++++++++++++++
 4 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/.gitignore b/.gitignore
index 3da165e07c77c..df7002a79d974 100644
--- a/.gitignore
+++ b/.gitignore
@@ -38,3 +38,6 @@ pandas/io/*.json
 .vagrant
 *.whl
 **/wheelhouse/*
+
+.project
+.pydevproject
diff --git a/doc/source/release.rst b/doc/source/release.rst
index ffb792ca98da5..1e1b665a478a1 100644
--- a/doc/source/release.rst
+++ b/doc/source/release.rst
@@ -433,6 +433,7 @@ Bug Fixes
   - Fix an issue in TextFileReader w/ Python engine (i.e. PythonParser)
     with thousands != "," (:issue:`4596`)
   - Bug in getitem with a duplicate index when using where (:issue:`4879`)
+  - Fixed ``_ensure_numeric`` does not check for complex numbers (:issue:`4902`)
 
 
 pandas 0.12.0
diff --git a/pandas/core/nanops.py b/pandas/core/nanops.py
index 3a185ca83604d..247f429d4b331 100644
--- a/pandas/core/nanops.py
+++ b/pandas/core/nanops.py
@@ -546,12 +546,14 @@ def _ensure_numeric(x):
     if isinstance(x, np.ndarray):
         if x.dtype == np.object_:
             x = x.astype(np.float64)
-    elif not (com.is_float(x) or com.is_integer(x)):
+    elif not (com.is_float(x) or com.is_integer(x) or com.is_complex(x)):
         try:
             x = float(x)
         except Exception:
-            raise TypeError('Could not convert %s to numeric' % str(x))
-
+            try:
+                x = complex(x)
+            except Exception:
+                raise TypeError('Could not convert %s to numeric' % str(x))
     return x
 
 # NA-friendly array comparisons
diff --git a/pandas/tests/test_common.py b/pandas/tests/test_common.py
index 8c5764a3f59a6..740e3d0821cd7 100644
--- a/pandas/tests/test_common.py
+++ b/pandas/tests/test_common.py
@@ -14,6 +14,7 @@
 import pandas.core.common as com
 import pandas.util.testing as tm
 import pandas.core.config as cf
+from pandas.core import nanops
 
 _multiprocess_can_split_ = True
 
@@ -311,6 +312,54 @@ def test_ensure_int32():
     assert(result.dtype == np.int32)
 
 
+class TestEnsureNumeric(unittest.TestCase):
+    def test_numeric_values(self):
+        # Test integer
+        self.assertEqual(nanops._ensure_numeric(1), 1, 'Failed for int')
+        # Test float
+        self.assertEqual(nanops._ensure_numeric(1.1), 1.1, 'Failed for float')
+        # Test complex
+        self.assertEqual(nanops._ensure_numeric(1 + 2j), 1 + 2j,
+                         'Failed for complex')
+
+    def test_ndarray(self):
+        # Test numeric ndarray
+        values = np.array([1, 2, 3])
+        self.assertTrue(np.allclose(nanops._ensure_numeric(values), values),
+                        'Failed for numeric ndarray')
+
+        # Test object ndarray
+        o_values = values.astype(object)
+        self.assertTrue(np.allclose(nanops._ensure_numeric(o_values), values),
+                        'Failed for object ndarray')
+
+        # Test convertible string ndarray
+        s_values = np.array(['1', '2', '3'], dtype=object)
+        self.assertTrue(np.allclose(nanops._ensure_numeric(s_values), values),
+                        'Failed for convertible string ndarray')
+
+        # Test non-convertible string ndarray
+        s_values = np.array(['foo', 'bar', 'baz'], dtype=object)
+        self.assertRaises(ValueError,
+                          lambda: nanops._ensure_numeric(s_values))
+
+    def test_convertable_values(self):
+        self.assertTrue(np.allclose(nanops._ensure_numeric('1'), 1.0),
+                        'Failed for convertible integer string')
+        self.assertTrue(np.allclose(nanops._ensure_numeric('1.1'), 1.1),
+                        'Failed for convertible float string')
+        self.assertTrue(np.allclose(nanops._ensure_numeric('1+1j'), 1 + 1j),
+                        'Failed for convertible complex string')
+
+    def test_non_convertable_values(self):
+        self.assertRaises(TypeError,
+                          lambda: nanops._ensure_numeric('foo'))
+        self.assertRaises(TypeError,
+                          lambda: nanops._ensure_numeric({}))
+        self.assertRaises(TypeError,
+                          lambda: nanops._ensure_numeric([]))
+
+
 def test_ensure_platform_int():
 
     # verify that when we create certain types of indices